JPH11213539A - Balancer for optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the vibration of a direction vertical to a rotatry shaft which is thought t be generated by the offset of the centroid of a disk or the like, in short, of a direction parallel with the disk by sealing fluid in an annular hollow chamber which is to be fixed coaxially with the rotary shaft of a spindle motor which is to be used at the time of driving a disk. SOLUTION: It is preferable that the upper parts of the outside wall of the annular hollow chamber are constituted by being inclined outward and the specific gravity of fluid is >=1 and preferably is >=2. A main body housing 13 consisting of the hollow chamber in which a lid 12 is provided is made to be an inverse conical base and is made to be an annular shape at whose center a shaft hole 14 for the rotary shaft of this device is formed. Fluid whose specific gravity is adjusted is performed by using an oleic acid series material as solvent and a ferrite series material as solute is sealed in the housing by roughly one third of the volume of the housing 13 and at the time this device is installed horizontally, the fluid 11 is collected at a position nearer the rotary shaft and the position of the centriod of the fluid at the time of a non-rotation of a low rotation is existing at a shaft side and when a rotational speed is raised, the centriod of the fluid is moved to the outer side and a moment of inertia becomes large and a vibration damping effect is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to audio equipment, video equipment, various precision equipment, especially CD, LD, CD-ROM, D
The present invention relates to a vibration damping structure for a device using a media disk (hereinafter referred to as a disk) of a device (hereinafter referred to as a device) for storing or reproducing data on a non-contact disk information medium such as an optical disk such as a VD or a DVD-ROM or a magneto-optical disk. Things.

2. Description of the Related Art Conventionally, in an optical disk, a magneto-optical disk or the like, as shown in FIG. 1, a rotating body (hereinafter referred to as a rotating body) composed of a clamper body 1, a disk 2, a turntable 3, and a spindle motor 4. Generally, a mechanical chassis 6 composed of a pickup 5 is supported by a damper 7 made of an elastic body.
The characteristic required of the damper 7 is to prevent vibration from the outside of the apparatus (hereinafter referred to as disturbance vibration) in order to keep the relative distance between the disk 2 and the pickup 5 constant and to support it.

In recent years, with an increase in the speed of an optical disc device (20 times speed; rotation speed, 24 times speed; rotation speed), unbalance during rotation of rotating components such as the disk 2 and the turntable 3 has been increased. Causes vibration in the direction perpendicular to the rotation axis, that is, in the direction parallel to the disk. However, the conventional damper 7 is effective against disturbance vibrations, but cannot provide a sufficient effect on vibrations in the parallel direction (hereinafter referred to as internal disturbance vibrations) generated from rotating bodies in these devices. When the natural frequency of the damper 7 is close to the vibration generated from the rotating body, resonance occurs, and the amplitude of the mechanical chassis increases. Therefore, there is a need to simultaneously perform the control of disturbance vibration and the control of disturbance vibration by the damper 7 which have been conventionally performed. In recent trends, a balancer mechanism using an iron ball 8 as shown in FIG. 2 has been proposed as a solution to the above-mentioned problems. There are problems such as very difficult balance control.

SUMMARY OF THE INVENTION The present invention makes it possible to attenuate internal vibration by adding a balancer in which a fluid is sealed in a rotating body. The present invention exerts the effect of a balancer by causing the fluid to move in the opposite direction to the position of the center of gravity of the disturbance vibration generated by the deviation of the center of gravity (hereinafter referred to as the center of gravity) by the rotating body, thereby enabling the control of the disturbance vibration. The effect of the balancer is caused by the volume of the fluid sealed in the annular hollow chamber fixed coaxially with the rotation axis and the specific gravity of the fluid. However, since the capacity is fixed by the shape of the balancer, it is necessary to control the effect of the balancer by the specific gravity of the fluid, and it is considered that a specific gravity of the fluid of 1 or more is effective, but a specific gravity of 2 or more Is preferable because the balancer effect can be easily controlled. Fluid materials include, for example, water-based, stearic acid-based, alcohol-based, and the like, which have a dispersing agent added or dispersed as needed, and oleic acid-based, linol-based materials that exhibit a dispersing effect by themselves. Acids and the like are included, and solutes include ferrites, aluminas, magnesium oxides, brass, and the like, but are not limited thereto. Also, mercury or the like is effective as the high specific gravity fluid. The viscosity of the fluid is desirably about 5,000 cp or less in consideration of fluidity. Furthermore, the present invention
The use of the fluid is characterized in that it is possible to prevent noise during disk rotation, which is a problem in balancers using iron balls or the like. The theory used for the optical disk balancer of the present invention is shown in FIG.
When a model as shown in the following is used, as shown in the following equation 1, the relationship between the eccentricity of the disk 2 and the eccentricity of the optical disk balancer 10 attached to the rotating shaft 9 is expressed by the following equation 1.
When it satisfies, it is considered particularly effective. m × I = m ′ × I ′ (1) where m is the weight of the disk, I is the distance from the center of the rotation axis to the position of the center of gravity of the disk (in the direction perpendicular to the rotation axis), and m ′ is the weight of the balancer for the optical disk. I ′: distance from the center of the rotation axis to the position of the center of gravity of the optical disk balancer (in the direction perpendicular to the rotation axis). Even when m × I> m ′ × I ′, the effect of damping internal vibration is effective.

FIG. 4 is a sectional view showing an embodiment of an optical disk balancer according to the present invention. The main body container 13 composed of a hollow chamber with a lid 12 is in the shape of an inverted truncated cone, and has an annular shape in which a shaft hole 14 for a rotation shaft of the device is formed in the center. A fluid whose specific gravity has been adjusted by using an oleic acid-based solvent and a ferrite-based solute is sealed in the container to about ３ of the volume. With the above configuration, in the present invention, when installed horizontally, the fluid 11 is collected at a position closer to the rotating shaft, and the center of gravity of the fluid at the time of non-rotation or at the time of low rotation speed is located on the shaft side. When the rotation speed increases, the position of the center of gravity of the fluid moves outward, the moment of inertia of the fluid increases, and the vibration damping effect increases. Thus, the balancer of the present invention
It is variable according to the rotation speed. FIG. 5 shows a configuration when the optical disk balancer 10 is installed on a rotating body. In the present embodiment, the main body lid 12, the main body container 1
3 used acrylonitrile-butadiene-styrene resin (ABS), but other materials include metals such as brass (BSBM), copper (Cu), aluminum (Al), iron (Fe), and stainless steel (SUS). And polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), acrylonitrile-styrene-acrylate resin (ASA), polyamide (PA), polyacetal (POM), polycarbonate (PC), polyethylene Terephthalate (P
ET), polybutylene terephthalate (PBT), polyphenylene oxide (PPO), polyphenylene sulfide (PPS), epoxy resin (EP), silicone resin (Si), and polyurethane (PUR). Further, the shape of the main body container may be an annular hollow chamber in which the upper part of the outer wall is inclined outward, and for example, may have an inverted conical shape.

[Embodiment 1] In this embodiment, in order to give the balancer the eccentricity of the fluid itself, about 1/3 of the volume of the main body container 13 is provided.
A fluid having a specific gravity d = 1 was sealed so that At this time,
The weight of the balancer, that is, m ′ in Equation 1, is given by the following Equation 2.
Represented by m ′ = M × d Equation 2

## EQU2 ## where M: enclosed volume of fluid, d: specific gravity of fluid.

Example 2 A fluid 11 having a specific gravity d = 2 was used.

Embodiment 3 A fluid 11 having a specific gravity d = 3 is used.

Embodiment 4 A fluid 11 having a specific gravity d = 4 is used.

Embodiment 5 A fluid 11 having a specific gravity d = 5 is used.

Embodiment 6 A fluid 11 having a specific gravity d = 6 is used. Comparative Example 1 This comparative example has a conventional structure in which a mechanical chassis is supported by a damper. Table 1 shows the results of measurement of acceleration (G value) for the cases using Examples 1 to 6 described above, together with Comparative Example 1.

The measurement was carried out using an eccentric disk (m in Equation 1).
× 1 = 1 g · cm), and the acceleration (measured by a mechanical shake test in the direction parallel to the disk when the disk is rotated on a 24 × -speed CD-ROM (when the CD-ROM is reading information on the disk: about 115 Hz)) G value) was measured. Further, in this measurement, the damper 7 supporting the mechanical chassis 6 is set at a natural frequency of about 50 Hz.

According to the balancer for an optical disk of the present invention, it is possible to obtain the effect of suppressing vibration in the direction perpendicular to the rotation axis, which is considered to be caused by the deviation of the center of gravity of the disk, that is, the direction parallel to the disk, that is, the vibration suppression effect. Was. By obtaining this effect, it is possible to suppress not only disturbance vibration which is damped by the conventional damper but also disturbance vibration which has not been sufficiently solved until now. The speed of reading information expected to be further advanced in the future disk information media is considered to increase the problem of internal vibration, so that the present invention can cope with any vibration. It is particularly effective for the constant angular velocity system (CAV).

[Brief description of the drawings]

FIG. 1 is a sectional view of a disc reproducing apparatus.

FIG. 2 is a schematic sectional view of a balancer mechanism using an iron ball.

FIG. 3 is a model diagram relating to Equation 1 showing the relationship between the disk eccentricity and the optical disk balancer eccentricity.

FIG. 4 is a cross-sectional view of the product of the present invention in Examples 1 to 6.

FIG. 5 is a sectional view of an installation structure of the product of the present invention in the first to sixth embodiments.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Clamper body 2 Disk 3 Turntable 4 Motor 5 Pickup 6 Mechanical chassis 7 Damper 8 Iron ball 9 Rotating shaft 10 Optical disk balancer 11 Fluid 12 Main body cover 13 Main body container

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[Procedure amendment]

[Submission date] March 11, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

[0030]

[Table 1] This measurement was performed using an eccentric disk (m × 1 = 1 in Equation 1).
g · cm) and acceleration (G value) by a mechanical shake test in a direction parallel to the disk when the disk is rotated on a 24 × -speed CD-ROM (when the CD-ROM is reading information on the disk: about 115 Hz). A measurement was made. Further, in this measurement, the damper 7 supporting the mechanical chassis 6 is set at a natural frequency of about 50 Hz.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

FIG. 3

FIG. 4

FIG. 5

Claims (3)

[Claims] An optical disk balancer which is coaxially fixed to a rotating shaft of a spindle motor used when driving a disk and has a fluid enclosed in an annular hollow chamber. 2. The optical disk balancer according to claim 1, wherein an outer wall of the annular hollow chamber has an upper portion inclined outward. 3. The balancer for an optical disk according to claim 1, wherein the specific gravity of the fluid is 1 or more.