JPS635810B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for externally scattering lubricating oil for braking in a voice coil type electromagnetic drive system, and particularly relates to a method for dispersing lubricating oil externally in a voice coil type electromagnetic drive system, and in particular, an opening larger than the gap length of a permanent magnet gap at the tip of a voice coil suspension disk. A braking lubricant scattering receiving part is formed downward by holding it, and a round washer-shaped non-magnetic material with an inclined surface from the top of the inner periphery to the bottom of the inner periphery is attached to the top surface of the permanent magnet. It consists of a round washer-shaped non-magnetic material with a downwardly inclined surface attached to the upper surface of the magnetic material, and a scattering damping lubricating oil return section, which scatters from the permanent magnet gap when the voice coil is driven at high speed. The braking oil is received by the braking oil scattering receiving part, and the falling braking oil is returned to the permanent magnet gap through the scattering braking oil returning part, so that the braking oil is scattered outside. This invention relates to a method for preventing external scattering of braking oil in a voice coil type electromagnetic drive system.

Conventionally, a so-called voice coil type electromagnetic drive system has been used as an electromagnetic drive system for optical pickup actuators, speakers, and other control equipment.

As an example, an actuator for an optical pickup will be explained based on FIG. A permanent magnet gap 3 is formed as a channel, and a circular boil coil 4 is arranged in the permanent magnet gap 3. The voice coil 4 is suspended and supported by a voice coil suspension disk 7 that protrudes from a lens barrel 6 on which an objective lens 5 is attached.
is supported by upper and lower parallel leaf springs 8 so as to be freely movable in the vertical direction. and,
Since the magnetic flux of the permanent magnet 1 and the current flowing through the voice coil 4 are perpendicular to each other, according to Fleming's left hand rule, the voice coil 4, which is a movable part, receives a force in the vertical direction, and the lens barrel 6 and the objective This is to move the lens 5 in the vertical direction. Here,
When no lubricating oil is put into this cavity 3, as shown in Figure 2, the resonance peak is large (solid line).
However, in this case, if the resonance frequency deviates slightly due to temperature change, etc., the control system becomes unstable, so a characteristic (dotted line) with a resonance peak as small as possible is preferable. Therefore, as shown in FIG. 3, for braking purposes, a brake lubricating oil 9, such as oil or a magnetic fluid that also has the effect of improving magnetic efficiency, is applied to the permanent magnet gap 3 and the voice. It is inserted between the coils 4.

However, in this prior art, in the case of low-speed drive, the brake lubricant 9 does not scatter, but in the case of high-speed drive (large amplitude and high frequency), the brake lubricant 9 is placed outside, for example, by a permanent magnet 1. , scattered on the upper surface of the characteristic body 2. As a result, the braking oil 9
If there is a shortage, there is a problem that the resonance peak becomes large and the control system becomes unstable.

This invention was made by focusing on the problems of the prior art as described above, and includes a damper which is formed downward at the tip of a voice coil hanging disk with a frontage larger than the gap length of the permanent magnet gap. A round washer-shaped non-magnetic material with a sloped surface from the top inner surface to the bottom surface of the inner periphery is attached to the top surface of the permanent magnet, and a round washer shape with a sloped surface from the top surface of the outer periphery to the bottom surface of the outer periphery is attached to the top surface of the permanent magnet. A scattering braking oil return section is formed by attaching a non-magnetic material to the upper surface of a magnetic material, and when the voice coil is driven at high speed, the braking oil returning section is formed by attaching a non-magnetic material to the upper surface of the magnetic material. It is an object of the present invention to solve the above-mentioned problems by receiving the falling brake lubricating oil in the oil scattering receiving part and returning it to the permanent magnet cavity through the scattering braking oil returning part.

The present invention will be explained below based on the drawings.

FIG. 4 is a sectional view showing an embodiment of the present invention.

Reference numeral 10 denotes a braking oil scattering receiving portion, which is formed at the tip of the voice coil suspension disk 7 so as to face downward. The braking lubricant scattering receiving part 10 has an inverted V-shaped cross section or an upper semicircular cutout with the voice coil 4 at the center, and the opening W thereof is set to be larger than the gap length D of the permanent magnet cavity 3. ing. Thereby, the brake lubricant 9 scattered from the permanent magnet cavity 3 is received by the brake lubricant scattering receiving part, and does not scatter to the outside. 11 is a lubricant return part for scattering braking,
It is formed from an outer non-magnetic material 12 and an inner non-magnetic plate 13. The outer non-magnetic material 12 is attached to the upper surface of the permanent magnet 1 in the shape of a round washer having an inclined surface from the upper inner surface to the lower inner surface. The inner non-magnetic material 13 is attached to the upper surface of the magnetic material 2 in the shape of a round washer having an inclined surface from the upper surface to the lower surface of the outer periphery. The inclined surfaces of the outer non-magnetic body 12 and the inner non-magnetic body 13 are arranged so that the braking oil 9 falling from the braking oil scattering receiving part 10 is quickly returned to the permanent magnet cavity 3. , as steep as possible, within acceptable limits. Further, although not shown, grooves may be provided on the inclined surface. With this configuration, when the voice coil 4 is driven at high speed, even if the braking oil 9 filled in the permanent magnet cavity 3
Even if it scatters, the scattered amount is caught by the braking oil scattering receiving part 10 and falls, and the scattering braking oil returning part 11 prevents it from falling on the upper surface of the permanent magnet 1 and the magnetic body 2. It is returned to the permanent magnet cavity 3 and is not scattered outside. As explained above, the present invention has a structure in which a brake oil scattering receiving part is formed on the voice coil suspension disk, and a scattering braking oil return part is formed in the upper part of the permanent magnet cavity. Since it is possible to prevent the braking lubricating oil from scattering to the outside, it is possible to reduce the resonance pick-up and to stabilize the control system.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the voice coil type electromagnetic drive system in an optical pickup, Fig. 2 is a diagram showing the relationship between frequency and gain, Fig. 3 is a diagram showing braking oil in the cavity, and Fig. 4 is a diagram showing the relationship between frequency and gain. The figure is a sectional view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Permanent magnet, 2... Magnetic body, 3... Permanent magnet cavity, 4... Voice coil, 5... Objective lens, 6... Lens tube, 7... Voice coil hanging disk, 8... ... Parallel leaf spring, 9 ... Braking oil, 10
... Braking oil scattering receiving part, 11 ... Splashing braking oil return part, 12 ... Outer peripheral side non-magnetic material, 13 ...
Inner circumferential non-magnetic material.

Claims (1)

[Claims] 1. A voice coil type electromagnetic drive in which braking oil is filled between a permanent magnet gap, which is a magnetic path formed by a permanent magnet and a magnetic body, and a voice coil arranged in the permanent magnet gap. In the system, a braking oil scattering receiving part is formed downward with an opening larger than the gap length of the permanent magnet cavity at the tip of the voice coil hanging disk, and a part is inclined from the inner circumferential upper surface to the inner circumferential lower surface. A round washer-shaped outer non-magnetic material having a surface is attached to the upper surface of the permanent magnet, and a round washer-shaped inner non-magnetic material having an inclined surface from the upper outer surface to the lower outer surface is attached to the upper surface of the magnetic material. When the voice coil is driven at high speed, the brake oil scattered from the permanent magnet gap is received by the brake oil scattering receiving part and falls. A method for preventing external scattering of braking oil in a voice coil type electromagnetic drive system, which prevents external scattering of braking oil by returning control oil to the permanent magnet cavity through the scattering braking oil return section. .