VIBRATION-REDUCING DEVICE FOR HIGH-SPEED ROTATIONAL BODY

FIELD OF THE INVENTION

[0001] The present invention relates to a vibration-reducing device for high-speed rotational body, more particularly, to a vibration-reducing device, by which the data reading/writing device such as CDROM has less vibration and better data accessing stability.

BACKGROUND OF THE INVENTION

[0002] As the accessing speed of CDROM increases, the vibration problem due to acentric and high speed rotation thereof. As a result, the data accessing s influence and the user will feel uncomfortable. Therefore, a vibration-reducing device is required for the high-speed CDROM.

[0003] The conventional vibration-reducing device generally uses elastomer such as rubber or silicon rubber as hanging means between a weight body and the reading device to be suppressed vibration. However, the hanging means made of such elastomer has large variation in characteristics due to the difficulty in controlling the hardness and elastic constant (Young's modulus) of the elastomer materials. Therefore, the vibration-reducing effect is degraded and fail to meet the specifically-designed requirement. Moreover, the mechanical properties of the elastomer, such as elastic constant, hardness and damping ratio, are highly thermal dependent. The designed parameters of the hanging means even has great variation over an ordinary environment (5° C. ˜u60° C.), thus degrades the vibration-reducing effect.

[0004] It is an object of the invention to provide a vibration-reducing device, wherein metal wire or metal plate is used to replace the elastomer member as hanging means between the weight body and the reading device. The mechanical properties of metal materials have a great similarity over the different batches of product such that metal materials are advantageous to use as hanging means between the weight body and the reading device. Moreover, the mechanical properties of metal materials are less thermal sensitive in ordinary environment (5° C. ˜60° C.), thus provides enhanced stability.

[0005] The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which:

BRIEF DESCRIPTION OF DRAWING

[0006]
FIG. 1 shows the model of spring-mass system for the present invention;

[0007]
FIG. 2 shows the relationship between vibrational displacement and the angular speed of the optical disk to be accessed;

[0008]
FIG. 3 is the perspective view of the invention;

[0009]
FIG. 4 is the perspective view of the first embodiment of hanging means in the present invention;

[0010]
FIG. 5 is the perspective view of the second embodiment of hanging means in the present invention;

[0011]
FIG. 6 is the perspective view of the third embodiment of hanging means in the present invention; and

[0012]
FIG. 7 is the perspective view of the fourth embodiment of hanging means in the present invention.

DETAIL DESCRIPTION OF PREFERRED EMBODIMENT

[0013] As shown in FIG. 1, the principle of the vibration-reducing device of the present invention can be explained with reference a model of spring-mass system, wherein A denotes the housing of the reading device, m1 the reading device, m2 the weight body, k1, C1 the elastic constant and damping constant of the hanging means between the reading device and the housing, k2, C2 the elastic constant and damping constant of the hanging means between the reading device and the weight body. F0 the centrifugal force of the reading device and ω the angular speed of the disk.

[0014] The high-speed CDROM is generally designed to operate in constant angular speed and k2/m2 is designed to be square of the angular speed, i.e.

ω2=k2/m2

[0015] The vibration of the reading device caused by the acentric disk will transfer to the weight body (m2) at the designed angular speed. The vibration of the reading device will be reduced by the transferring action.

[0016] For sake of explanation, provided that C1═C2═0 in above hanging means, the vibration X1 of the reading device can be expressed as

\frac{X, k_{1}}{F_{0}} = \frac{[1 - {(\frac{ω}{ω_{22}})}^{2}]}{[1 + \frac{k_{2}}{k_{1}} {(\frac{ω}{ω_{11}})}^{2}] [1 - \frac{k_{2}}{k_{1}} {(\frac{ω}{ω_{22}})}^{2}]}

[0017] wherein ω112=k1/m1, and ω222=k2/m2 The vibration of the reading device is zero when the angular speed of the disk is the designed value, i.e., ω/ω22=ωdisk/ω22=1. FIG. 2 shows the variation of X1k1/F0 with ω/10722 and provided that u=m2/m1=0.2 and ω22/ω11=1.0. As shown in this figure, the vibration X1 is very sensitive to ω/ω22. The vibration-reducing effect will be degraded and the vibration is seriously increased, even w slightly deviates from ω22. In other word, the parameters k2 and m2, should be well controlled to ensure the quantity ω22(={square root}{square root over (k2/m2)}). The present invention uses the fact that metal materials have stable thermal properties to keep k2 at constant value for mass production.

[0018] As shown in FIG. 3, the present invention comprises a reading device, 10 and a weight body 20, wherein the reading device 10 comprises at least one disk rotating means 11 and the weight body can be any object with sufficient weight above or under the reading device. The present invention is characterized in that the conventional elastomer is replaced by metal wire or metal plate to function as hanging means between the reading device 10 and the weight body 20. The hanging means 30 can be fixed between the reading device 10 and the weight body 20 by screw 40.

[0019] As shown in FIGS. 4 to 6, the hanging means 30 of the present invention is made of metal wire and can be bent to desired shape. Both ends of the hanging means 30 are bent to form loop 31 such that the hanging means 30 can be fixed between the reading device 10 and the weight body 20 by screw 40.

[0020] As shown in FIG. 7, the hanging means 30 of the present invention is made of metal plate and can be bent to desired shape. Both ends of the hanging means 30 are bent to on loop 31 such that the hanging means 30 can be fixed between the reading device 10 and the weight body 20 by screw 40.

[0021] In the present invention, the mechanical properties of metal materials have a great similarity over the different batches of product such that metal materials are advantageous to use as hanging means between the weight body and the reading device. Moreover, the mechanical properties of metal materials are less thermal sensitive in ordinary environment (5° C. ˜60° C.), thus provides enhanced stability.

[0022] Although the present invention has been described with reference to the preferred embodiment thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have suggested in the foregoing description, and other will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.

VIBRATION-REDUCING DEVICE FOR HIGH-SPEED ROTATIONAL BODY

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