JPH02139758A - Device for adjusting inequilibrium of rotation of information recording medium - Google Patents

Abstract

PURPOSE:To cancel horizontal inertia force generated due to the eccentricity of a rotational center and to obtain stable rotation by forming a liquid tank on the outer edge part of an information recording medium. CONSTITUTION:The ring-like liquid tank 6 is arranged along the outer edge part of the recording medium 1 and stuck to the end face of the outer edge part so that the inside of the tank 6 is sealed. A liquid 7 with a high specific gravity such as mercury is sealed inside the tank 6 together with air and the liquid 7 can be freely moved in the inside. When the recording medium 1 starts to rotate by the driving force of a driving motor 3, volume force F1 is generated due to eccentricity on the center point O of rotation. On the other hand, the liquid 7 in the tank 6 is moved in the reverse direction against the volume force F1 and distributed eccentrically to a part close to the center O. Thereby, the volume force F2 due to the liquid 7 is applied in a direction canceling the volume force F1 due to the eccentricity of the center point O and horizontal force applied to a rotational driving shaft 2 is canceled, so that stable rotation can be obtained.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is an information recording and reproducing device that records and reproduces information by rotating a disk-shaped information recording medium. The present invention relates to a rotational imbalance adjustment device for an information recording medium for eliminating imbalance.

[Prior Art] Conventionally, information has been recorded and recorded using a disk-shaped information recording medium.
In a reproduction device, the entire area of the information recording section is traced by moving the head in the radial direction of the recording medium while rotating the recording medium. FIG. 6 is a plan view of the recording medium 1, in which a rotational center hole 1a is provided near the center of the recording medium 1 having an information recording section, which engages with the rotational drive shaft 2 of the recording/reproducing device. The recording medium l is positioned. Generally, the center point O of the rotation center hole 1a does not coincide with the shape center 1b of the recording medium 1, and some eccentricity is observed.

FIG. 7 is a side view of the rotary drive device, in which the rotary drive shaft 2 is directly connected to a drive motor 3, and a recording medium holder 4 is attached. Further, the presser portion 5 is fitted onto the rotary drive shaft 2 and is detachable, and together with the recording medium holding portion 4, holds the recording medium 1 from above and below.

The recording medium l fixed to the recording medium holder 4 rotates clockwise by the driving force of the drive motor 3, but as shown in FIG.
does not overlap with the outer periphery of the recording medium l, and its protruding portion B
1 and B2 generate a body force F1 shown by an arrow from the center point 0 to the shape center 1b. Therefore, the rotary drive shaft 2 is always subjected to a load in the horizontal direction, which prevents stable rotation.

[Object of the Invention] An object of the present invention is to correct the imbalance of rotating mass that occurs when the center of shape of the recording medium and the center of rotation do not coincide with each other, and to obtain stable rotation of an information recording medium. An object of the present invention is to provide an imbalance adjustment device.

[Summary of the invention] The gist of the present invention is to achieve the above objects.

This is a rotational imbalance adjustment device for an information recording medium, characterized in that a ring-shaped liquid tank is provided on the outer periphery of a disk-shaped information recording medium, and a liquid and gas are sealed inside the liquid tank.

[Embodiments of the Invention] The present invention will be described in detail based on embodiments illustrated in FIGS. 1 to 5.

1 and 2 show a first embodiment, and the same reference numerals as in FIGS. 6 and 7 indicate the same members. A ring-shaped liquid tank 6 is provided along the outer edge of the recording medium 1, and this liquid tank 6 is adhered to the end surface of the outer edge of the recording medium 1 so that the inside thereof is sealed. Further, a high specific gravity liquid 7 such as mercury is sealed together with air inside the liquid tank 6, and the liquid 7 can freely move inside.

As shown in FIGS. 3 and 4, when the recording medium 1 starts rotating due to the driving force of the drive motor 3, a body force F1 is generated due to the eccentricity of the center point 0 of rotation. On the other hand, the liquid 7 inside the liquid tank 6 moves in the direction opposite to the body force F1, and is distributed biased toward the portion near the center point 0.

As a result, the body force F2 due to the liquid 7 cancels the body force F1 due to the eccentricity of the center point O (@), and if the capacity of the liquid tank 6 and the amount of the liquid 7 are sufficient, Fl + F2 = 0, The horizontal force applied to the rotary drive shaft 2 is completely canceled out.

FIG. 5 shows a second embodiment, in which a ring-shaped liquid tank 8 is fitted with the outer edge of the recording medium 1 to obtain a removable attachment, and the inside contains liquid 7 and air. is sealed,
The liquid 7 can freely move inside as in the first embodiment.

In this case, since the liquid tank 6 can be attached to and detached from all the recording media 1 having the same shape, it can be used without increasing the molding cost of the recording medium 1 itself.

[Effect of the Invention J As explained above, the rotational imbalance adjustment device for an information recording medium according to the present invention provides a liquid tank at the outer edge of an information recording medium in the form of a recording medium, thereby reducing horizontal imbalance caused by eccentricity of the center of one rotation. The directional inertia force is canceled out, stable rotation is obtained, and the life of the one-rotation bearing can be extended. Further, since there is no problem even if the standard of eccentricity accuracy of the rotation center hole is relaxed, the cost of molding the recording medium itself becomes low.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the rotational imbalance adjustment device for an information recording medium according to the present invention, and FIG. 1 is a plan view, and FIG.
The figure is a sectional view taken along the line xx' of Fig. 1, Fig. 3 is a plan view of the operating state, Fig. 4 is a sectional view taken along the line Y-Y' of Fig. 3, and Fig. 5 is a sectional view taken along the line XX' of Fig. 3. FIG. 6 is a plan view of the conventional example, and FIG. 7 is a side view of the conventional example. 1 is a recording medium, 2 is a rotary drive shaft, 3 is a drive motor,
4 is a recording medium holding part, 5 is a holding part, 6°8 is a liquid tank, 7
is a liquid. Patent applicant: Canon Co., Ltd. Drawings Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A rotation imbalance adjustment device for an information recording medium, characterized in that a ring-shaped liquid tank is provided on the outer periphery of a disk-shaped information recording medium, and a liquid and gas are sealed inside the liquid tank.