JPH1027439A - Carriage unit for optical head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carriage unit for optical heads which is light in weight, is capable of dealing with a trend toward higher speeds and is inexpensive. SOLUTION: The carriage unit 1 for optical heads consists of a carriage 3 on which the optical head 2 is mounted and which is freely movably guided in the radial direction of a disk by means of two rails 4 via a plurality of bearings. The bearings 5a on a right side are formed as sliding bearings made of synthetic resins which are disposed at two points apart in the moving direction of the carriage 3 and have the bore surfaces sliding and rotating with a shaft part 11 supported at the carriage 3 and the outside diameter surfaces coming into rolling contact with the rails 4 at two points in a vertical direction. The bearing 5b on the left side is formed as a sliding bearing made of a synthetic resin which is disposed at one point in the central part in the axial direction of the carriage 3 and comes into sliding contact with the rails 4 at the two points in the vertical direction. The bearing 5b is elastically supported at the carriage 3 via leaf springs in order to impart a prepressure to the respective bearings 5a, 5b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head carriage unit for an optical disk drive, and more particularly to an optical head carriage unit which is light in weight, has less rattling during movement, and is inexpensive.

[0002]

2. Description of the Related Art A magneto-optical disk drive a as shown in FIG. 8, for example, is known as an optical disk drive.
In this apparatus, a carriage unit c on which an optical head b is mounted is driven by a linear motor d to move in a radial direction of a magneto-optical disk e.

An optical head b is provided on the surface of the magneto-optical disk e.
The laser light f emitted from the objective lens g
Irradiated in the form of minute spots via the, the recorded information is reproduced and erased / recorded for writing new information. Erasure and recording of information on the magneto-optical disk e are performed by changing the direction of the magnetic field of the bias magnet h.

The carriage unit c on which the optical head b is mounted is connected to two rails j via a plurality of bearings n.
While being guided by the linear motor d. FIG.
10 shows an example of such a conventional optical head carriage unit c. The carriage m on which the optical head b is mounted is mounted on the magneto-optical disk by a rail j composed of two round bars via a total of six ball bearings n arranged on the one side and two on the other side and one on the other side. e is movably supported in the radial direction. One of the ball bearings n out of the total six is attached to the carriage m via an elastic member o for applying a preload, and is elastically supported by the carriage m. Other ball bearings n are mounted by inserting a pin shaft q into a pin hole p formed in an inclined portion on the side surface of the carriage m.

[0005]

In recent magneto-optical disk drives, there has been a remarkable demand for higher cost as well as higher speed. Therefore, the carriage unit c has been reduced in cost as well as weight. Is desired.

However, in the case of the conventional optical head carriage unit, at least six expensive ball bearings n are required, so that it is difficult to reduce the cost. Further, there is a limit to the reduction of the weight of the movable part and the speed is increased. There is a problem that it cannot be handled.

Further, if there is an error in the angle of the pin hole p for mounting the ball bearing n, the carriage unit c cannot travel smoothly, and it is necessary to increase the angle accuracy of the pin hole p. There is a problem that processing is difficult and costs increase if it is attempted to secure them.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide an inexpensive optical head carriage unit which is lightweight, adaptable to high-speed operation, and inexpensive.

[0009]

In order to achieve the above object, an optical head carriage unit according to the present invention comprises:
In an optical head carriage unit in which a carriage on which an optical head is mounted is guided and supported by two rails via a plurality of bearings so as to be movable in a radial direction of the disk, a carriage unit for one of the two rails is provided. The bearing includes a sliding bearing made of a synthetic resin having an inner diameter surface that slides and rotates on a shaft supported by the carriage and an outer diameter surface that comes into rolling contact with the one rail at two locations, and a bearing on the other rail side. The bearing is provided with a synthetic resin sliding bearing elastically supported by the carriage and making sliding contact with the other rail at two or more places.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a carriage unit for an optical head according to a first embodiment of the present invention, and FIG. 2 is a sectional view of a part of the front view of FIG.

In the carriage unit 1 for an optical head according to this embodiment, a plurality of carriages 3 on which an optical head 2 is mounted, and in the illustrated embodiment, three steps are provided vertically through three bearings. The discs are guided movably in the radial direction of the disc by rails 4 and 4 composed of two round bars arranged in parallel.

The three bearings are all composed of synthetic resin plain bearings. Two plain bearings 5a are spaced apart from each other in the moving direction of the carriage 3 on the rail 4 side arranged on the right side in FIG. And one sliding bearing 5 on the rail 4 side lower than the right rail arranged on the left side.
b is disposed at the center of the carriage 3 in the axial direction.

As the synthetic resin material of the sliding bearings 5a and 5b, a resin obtained by adding an abrasive, a solid lubricant, a wax or the like to POM (polyoxymethylene), PA
A resin composition having (polyamide) and PE (polyethylene) is preferred. When heat resistance is required for the plain bearings 5a and 5b, PPS (polyphenylene sulfide), P
ES (polyethersulfone), etc., which contain a solid lubricant such as graphite, molybdenum disulfide, wax, fluororesin, liquid crystal polymer, polyimide, carbon, etc., or an abrasion resistance improving substance alone or in combination, preferable.

In FIG. 2, the right sliding bearing 5a is disposed with its axis directed vertically, and a circumferential groove 6 having a V-shaped cross section is formed in the axially central outer diameter surface. . In the circumferential groove 6, the upper and lower slope portions 6a and 6b come into contact with the outer peripheral surface of the rail 4, respectively, so that the sliding bearing 5a comes into rolling contact with the rail 4 at two locations separated in the axial direction of the bearing 5a. I have. The sliding bearings 5a configured as described above are arranged separately from each other in the moving direction of the carriage 3 and are supported by shafts 7 supported and attached to the carriage 3, respectively. The shaft 7 is disposed below the carriage 3 with its axis oriented in the vertical direction, and the upper end is press-fitted and fixed to the carriage 3. An annular spacer 8 made of a copper alloy or the like having excellent slidability and an inner diameter surface of the sliding bearing 5a are sequentially fitted to the shaft 7, and the inner diameter surface of the sliding bearing 5a is
Is fitted with a small gap so that it can slide and rotate. In the fitted state, a retaining ring 9 is mounted on the lower end of the shaft 7 projecting downward from the slide bearing 5a, whereby the slide bearing 5 disposed on the right side in FIG.
a is rotatably held with respect to the shaft 7 while being sandwiched between the spacer 8 and the retaining ring 9.

The sliding bearing 5b on the left side in FIG. 2 is disposed at the center in the moving direction of the carriage 3, and a V-shaped axial groove 10 is provided on the side facing the rail 4 for moving the carriage 3. It is formed along the direction. The groove 10 has the upper and lower slope portions 10a and 10b in contact with the outer peripheral surface of the rail 4, so that the sliding bearing 5b is in sliding contact with the rail 4 at two vertically separated sides of the side facing the rail 4. It has become. The sliding bearing 5b is provided with a cylindrical shaft portion 11 whose axis is oriented in the left-right direction on the side away from the rail 4, and the shaft portion 11 is provided with a hole 12 formed in the left side wall of the carriage 3. Is inserted movably in the axial direction. The distal end of the shaft 11 protruding from the hole 12 is pressed toward the rail 4 by a leaf spring 13 attached to the carriage 3, whereby the sliding bearing 5 b
Are elastically supported by the carriage 3. The leaf spring 13 is formed in a plate shape, and the upper end is fixed to the upper end of the left side wall of the carriage 3, and the lower end extends obliquely to the lower right and presses the tip of the shaft 11. Since the shaft portion 11 is rotatable, the sliding surface of the rail 4 and the sliding bearing 5b
Can be easily matched with the sliding surface, and therefore, the contact of each sliding surface is uniform and the wear resistance is excellent.

The carriage 3 is connected to each of the sliding bearings 5.
a, 5b, the circumferential groove 6 formed on the outer diameter surface of each right slide bearing 5a in FIG.
The upper and lower slope portions 6a and 6b contact the outer peripheral surface of the rail 4, respectively, and the right sliding bearing 5a comes into rolling contact with the rail 4 at two locations separated in the axial direction of the bearing 5a, and the rail 4 of the sliding bearing 5b. The upper and lower slope portions 10a and 10b of the groove 10 formed on the side facing the outer surface contact the outer peripheral surface of the rail 4,
The sliding bearing 5b comes into sliding contact with the rail 4 at two locations vertically separated from the bearing 5b.
Are movably guided and supported in the radial direction of the disk.

At this time, since the left slide bearing 5b is pressed by the elastic force of the leaf spring 13 fixed to the carriage 3, a horizontal (left-right) preload is applied to each slide bearing 5a, 5b. The preload is applied to the sliding bearing 5
A force that is substantially perpendicular to the rotation axis of a and perpendicular to the rails 4 absorbs bending and parallelism errors of the two rails 4.

Further, since the two rails 4 and 4 are disposed with a vertical step, a vertical (up-down) preload is applied to each of the slide bearings 5a and 5b.
Vertical play is prevented between the slide bearings 5a, 5b and the rail 4. In this case, the sliding bearing 5 in contact with the higher rail 4 arranged on the right side in FIG.
a, an upward force is applied, and a downward force is applied to the sliding bearing 5b, which contacts the lower rail 4 disposed on the left side. In this embodiment, the sliding bearing contacts the higher rail 4. The upper end surface of 5a is brought into contact with annular spacer 8 made of a copper alloy or the like having excellent slidability, whereby spacer 8 functions as a thrust sliding bearing to ensure smooth rotation of sliding bearing 5a. ing. If a flange is provided at the lower end of the shaft 7, the retaining ring 9 need not be provided.

As described above, in the carriage unit for an optical head of this embodiment, since the sliding bearings 5a and 5b made of synthetic resin are used as the bearings, the bearings themselves are compared with the conventionally used ball bearings. In addition to the weight reduction, the bearing cost is greatly reduced. Further, since one slide bearing contacts two places separated in the vertical direction, that is, the circumferential direction of the rail 4, two ball bearings can be used as one slide bearing. As a result, the number of bearings can be reduced by that much, and as a result, the carriage unit can be significantly reduced in weight and can be adapted to higher speeds, and the manufacturing cost can be significantly reduced. .

Further, since the sliding bearing is structurally small in the number of parts and the number of bearings is small, the interval between the two rails 4 and 4 can be reduced. As a result, the size of the carriage 3 can be reduced. The weight can be reduced, and the weight of the carriage unit 1 can be further promoted.

Furthermore, the parallelism of the two rails 4 and 4 and the mounting accuracy of the shaft 7 and the shaft portion 11, which were necessary in the case of the ball bearing, are not so required, and the adjustment work during the assembly is almost unnecessary. Can be simplified.

Further, by using the synthetic resin sliding bearings 5a and 5b having excellent sliding properties and abrasion resistance as described above, low friction and excellent durability can be obtained. .

In the above-described embodiment, a horizontal (left-right) preload is applied to the slide bearings 5a and 5b using the leaf springs 13. However, the preload is applied to the rotation axis of the slide bearing 5a. The type and structure of the spring are not particularly limited as long as the force is substantially perpendicular to the rail 4 and the force is substantially perpendicular to the rail 4.
Instead, an elastic member other than a coil spring or a spring may be used.

Further, in the above embodiment, the two rails 4, 4 are disposed with a vertical step, but the two rails 4, 4 may have the same height. FIG. 3 shows a carriage unit for an optical head according to a second embodiment of the present invention. FIG. 3 is a sectional view of the left side wall of the carriage. Note that the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The points different from the first embodiment will be described. The spring for preloading is a coil spring 15, which is provided with a hole 12 on the left side surface of the left side wall of the carriage 3.
One end is inserted into a bottomed hole 16 formed so that its axis is parallel to the axis of the hole 12, and the other end is in contact with the back surface of the slide bearing 5b. A plurality of the bottomed holes 16 and the coil springs 15 are provided at predetermined intervals in the circumferential direction. Since the direction of the force due to the expansion and contraction of the coil spring 15 is perpendicular to the rail 4, a preload is applied perpendicular to the rotation axis of the slide bearing 5a. This configuration has an advantage that the preload spring does not need to be fixed. The other configuration and operation and effect are the same as those of the first embodiment, and the description thereof will be omitted. A circumferential groove having a diameter larger than the hole 12 is provided around the hole 12 on the left side surface of the left side wall of the carriage 3, and one coil having a diameter larger than the hole 12 is provided in the circumferential groove. Plain bearing 5b
A preload may be applied to the sliding bearing 5b in a direction in which the sliding bearing 5b and the left side wall of the carriage 3 are separated from each other.

FIGS. 4 and 5 show an optical head carriage unit according to a third embodiment of the present invention. 4 is a plan view, and FIG. 5 is a sectional view of a part of the front view of FIG. Note that the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The points different from the first embodiment will be described. The preload spring is a flat plate spring 17 extending in the moving direction of the carriage 3, and is attached to a projection 18 provided at an axial end of a left side wall of the carriage 3. A shaft 11 provided on the slide bearing 5b is rotatably supported at the center of the carriage 3 in the direction of movement of the carriage 3 by a leaf spring 17, and the tip of the shaft 11 is formed on the left side wall of the carriage 3. The hole 19 is loosely inserted. Since the bending direction of the leaf spring 17 is perpendicular to the rail 4, even if the slide bearing 5 b is directly attached to the leaf spring 17, a preload is applied perpendicular to the rail 4. The other configuration and operation and effect are the same as those of the first embodiment, and the description thereof will be omitted.

FIGS. 6 and 7 show an optical head carriage unit according to a fourth embodiment of the present invention. 6 is a plan view, and FIG. 7 is a sectional view showing a part of the front view of FIG. Note that the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The difference from the first embodiment is that the first embodiment
In this embodiment, the sliding bearing 5b is provided at one position in the center of the left side wall of the carriage 3 in the moving direction, whereas in this embodiment, the sliding bearing 5b is provided on the left side wall of the carriage 3. The point is that two places are provided apart from each other in the moving direction. In this case, there is an advantage that it is strong against a moment as compared with the first embodiment.
The other configuration and operation and effect are the same as those of the first embodiment, and the description thereof will be omitted.

[0030]

As is apparent from the above description, in the present invention, since a synthetic resin plain bearing is used as a bearing, the weight of the bearing itself can be reduced as compared with a conventional ball bearing. The bearing cost is greatly reduced, and one slide bearing contacts two places in the circumferential direction of the rail, so that two ball bearings are replaced with one slide bearing, reducing the number of bearings. As a result, the weight of the carriage unit can be significantly reduced, and the speed can be increased, and the manufacturing cost can be significantly reduced.

In addition, since the sliding bearing is structurally small in the number of parts and the number of bearings is small, the interval between the two rails can be reduced. As a result, the carriage can be reduced in size and weight. Thus, the weight of the carriage unit can be further reduced.

Further, the parallelism between the two rails and the mounting accuracy of the bearings required for the ball bearing are not so required, and the adjustment at the time of assembling is easy and the assembling work can be simplified.

[Brief description of the drawings]

FIG. 1 is a plan view of an optical head carriage unit according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a part of the front view of FIG. 1;

FIG. 3 is an explanatory view of a carriage unit for an optical head according to a second embodiment of the present invention, in which a side wall on the left side of the carriage is shown in a sectional view.

FIG. 4 is a plan view of an optical head carriage unit according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a part of the front view of FIG. 4;

FIG. 6 is a plan view of an optical head carriage unit according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view showing a part of the front view of FIG. 6;

FIG. 8 is an explanatory schematic diagram for explaining a magneto-optical disk drive.

FIG. 9 is a plan view of a conventional optical head carriage unit.

FIG. 10 is a sectional view showing a part of the front view of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical head carriage unit 2 ... Optical head 3 ... Carriage 4 ... Rail 5a ... Sliding bearing 5b ... Sliding bearing 7 ... Shaft 13 ... Leaf spring

Claims (1)

[Claims] An optical head carriage unit in which a carriage on which an optical head is mounted is guided and supported by two rails via a plurality of bearings so as to be movable in a radial direction of a disk. The bearing on one rail side includes a sliding bearing made of synthetic resin having an inner diameter surface that slides and rotates on a shaft supported by the carriage and an outer diameter surface that is in rolling contact with the one rail at two locations, A carriage unit for an optical head, characterized in that a bearing on the other rail side is provided with a synthetic resin sliding bearing elastically supported by the carriage and in sliding contact with the other rail at two or more places.