JPH0845736A - Linear motor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an inexpensive, downsized linear motor with a built-in speed sensor. A linear motor composed of a side yoke 5, a permanent magnet 3, a center yoke 4, and a coil 1 wound around a coil bobbin 2, in which a drive coil 7 and a sensor coil 6 are arranged in parallel to the coil bobbin 2. Winded recess 1
0 is provided, and the drive coil 7 and the sensor coil 6 are integrally provided in one linear motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a CD-ROM and a CD-ROM.
The present invention relates to a linear motor used for driving a pickup such as REC and FDD, and particularly to a linear motor with a built-in speed sensor.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a linear motor of this type has a side yoke 5 to which a permanent magnet 3 is adhered,
A drive linear motor A in which a coil bobbin 2 around which a drive coil 7 is wound and a center yoke are combined to form a magnetic circuit, a side yoke 5 to which a permanent magnet 3 is bonded,
Using two types of speed sensor linear motors B (small type for driving) that move simultaneously through a coil bobbin 2 around which the sensor coil 6 is wound and a stay of a pickup in which a magnetic circuit is formed by combining a center yoke. The method of controlling the applied voltage for driving by using the counter electromotive voltage of the speed sensor is adopted, and at least a pair of linear motors is required.

[0003]

Conventionally, since a pair of linear motors are separately manufactured at the time of mass production, the unit price of the linear motor is increased by one pair. Also, a high mold is required. Further, since the space occupied by the linear motor cannot be reduced even inside the equipment, there are drawbacks such as downsizing and high cost.

An object of the present invention is to provide an inexpensive and small-sized linear motor while ensuring performance equivalent to that of a conventional product.

[0005]

According to the present invention, a winding is arranged on the outer peripheral portion of the coil bobbin, and a through hole capable of reciprocating in the longitudinal direction of the center yoke is provided on the inner peripheral portion of the coil bobbin. In a linear motor in which at least one of the arranged side yokes is arranged with respect to the center yoke to form a magnetic circuit, the winding of the coil bobbin includes a drive coil portion and a sensor coil portion. A linear motor is obtained.

[0006]

In the linear motor of the present invention, the side yoke, the center yoke, the permanent magnet, the coil bobbin around which the drive coil and the sensor coil are wound to form a magnetic circuit, and the center yoke is connected via the center yoke. The drive coil wound around the penetrating coil bobbin reciprocates according to Fleming's law by applying a coil current on the center yoke. Also, in order to detect the speed of movement, by arranging the sensor coil (without applying current) in parallel or in series on the same coil bobbin as the drive coil, the same movement as the drive coil is performed. A counter electromotive voltage is generated, and the speed of the drive coil is detected at the same time by the output voltage from the sensor coil. Since a speed sensor is incorporated in the drive linear motor, only one linear motor is required, cost can be reduced, and size can be reduced.

[0007]

FIG. 2 shows a coil cross-sectional view of a coil bobbin used in the first and second embodiments of the present invention. The coil bobbin 2 has a cylindrical shape, has a recess 10 in which the drive coil 7 and the sensor coil 6 are installed in parallel, and has a through hole 9 for sliding the center yoke.

FIG. 1 is a front view showing a linear motor with a built-in speed sensor according to a first embodiment of the present invention. A linear motor with a built-in speed sensor, which is a first embodiment of the present invention, includes a coil bobbin 2 having a driving coil and a sensor coil.
A side yoke 5, a permanent magnet 3, and a center yoke 4. The side yoke 5 is provided with the permanent magnet 3 having an N pole and an S pole in the thickness direction. And a magnetic circuit having a magnetic gap is formed. A coil bobbin 2 is arranged on the outer circumference of the center yoke 4, and a winding 1 having a drive coil and a sensor coil is arranged on the outer circumference of the coil bobbin 2. The coil bobbin 2 has a drive coil arranged inside and a sensor coil 6 arranged outside thereof. The drive coil moves in the direction of arrow 11 according to Fleming's law.

In the second embodiment, the coil bobbin 2 is provided with the sensor coil 6 inside the winding portion and the drive coil 7 outside.

FIG. 3 is a front view showing a linear motor with a built-in speed sensor according to a third embodiment of the present invention. The drive coil 7 is arranged on a part of the coil bobbin 2, and the sensor coil 6 is arranged in series on another part of the same coil bobbin.

FIG. 4 shows the drive coil 7 of the third embodiment.
A coil cross-sectional view in which the sensor coil 6 and the sensor coil 6 are arranged in series on the outer circumference of the same coil bobbin 2 is shown. That is, FIG.
As shown in, the coil bobbin 2 has the drive coil recess 12 and the sensor coil recess 13 provided on the same outer peripheral surface and winds the drive coil 7 and the sensor coil 6.

As described above, in the embodiment, the speed sensor linear motor is not required, and the same dimension as the conventional drive linear motor can be realized.

[0013]

According to the present invention, it is possible to provide a linear motor having the advantages of 1) low cost and 2) small size, while ensuring the performance equivalent to that of the conventional product.

[Brief description of drawings]

FIG. 1 is a front view showing a linear motor with a built-in speed sensor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of coils used in the linear motor with a built-in speed sensor according to the first and second embodiments of the present invention.

FIG. 3 is a front view showing a linear motor with a built-in speed sensor according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a coil used in a linear motor with a built-in speed sensor according to a third embodiment of the present invention.

FIG. 5 is a front view showing an example of a conventional linear motor. FIG. 5A is a front view showing a driving linear motor. Figure 5
(B) is a front view showing a linear motor for a speed sensor.

[Explanation of symbols]

 1 winding 2 coil bobbin 3 permanent magnet 4 center yoke 5 side yoke 6 sensor coil 7 drive coil 9 through hole 10 recess 11 arrow 12 drive coil recess 13 sensor coil recess A drive linear motor B speed sensor linear motor

Claims (1)

[Claims] 1. A side yoke having a winding arranged on an outer peripheral portion of a coil bobbin and having a through hole capable of reciprocating in a longitudinal direction of a center yoke on an inner peripheral portion of the coil bobbin and having a permanent magnet arranged on the center yoke. On the other hand, in a linear motor in which at least one is arranged to form a magnetic circuit, the winding of the coil bobbin includes a drive coil unit and a sensor coil unit.