JPH08280157A - Composite motor - Google Patents

Abstract

PURPOSE: To smoothly drive a body without causing rotational resonance by coupling the rotating shafts of a plurality of motors with each other through a coupling gear mechanism so that the rotation ratios between the shafts can become different from each other. CONSTITUTION: A pinion gear 11 which is meshed with a large-diameter gear 13 journaled by a shaft 12 installed to a chassis 5 is fixed to the lower surface of a turntable (driven body) for placing a disk. A small-diameter gear 14 integrally formed with the gear 13 is meshed with a pinion gear 17 installed to the rotating shaft of a sub-motor 15. The rotating shafts 7 and 16 of a main motor 6 and the sub-motor 15 are coupled with each other through a coupling gear mechanism 10 composed of the pinion gear 11, a large-diameter gear 13, a small-diameter gear 14, and a pinion gear 17 at a gear ratio of, for example, 1:2.5 so that the rotating shaft 16 of the sub-motor can make 0.4 revolution when the rotating shaft 7 of the motor 6 makes one revolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite motor having a plurality of motors whose rotary shafts are connected to each other and driving a driven body by simultaneously rotating these motors.

[0002]

2. Description of the Related Art The applicant of the present invention is Japanese Patent Application No. 6-152855.
Japanese Patent Application No. 6-152856 and Japanese Patent Application No. 6-164730
Proposes a composite type motor in which a driven body is driven by a composite type motor in which mutually rotating shafts are connected.

According to such a composite type motor, the driven body can be driven with sufficient torque by the inexpensive motor without using the expensive motor.

[0004]

However, in the above-mentioned device, since the rotating shafts of a plurality of motors are connected in a one-to-one manner by the connecting means, and the motors used are the same, the individual motors are not connected. Due to the overlapping of the rotational resonances, the driving torque increases as compared with the case of one motor, but the driven body vibrates due to the rotational resonance. For example, when the composite type motor is used as a spindle motor that rotationally drives a disc on which information is recorded, the disc vibrates and stable reproduction becomes difficult.

Further, when the rotation speed of the motor is minutely changed by CLV control during disk reproduction, vibration is generated by backlash of the gear in the case where the connecting means is composed of a gear, and this vibration is transmitted to the disk. Will end up.

[0006]

The motor comprises a plurality of motors for driving a driven body, and a connecting means for connecting the respective rotary shafts of the plurality of motors so that the rotation ratios thereof are different from each other.

[0007]

The driven body can be driven smoothly without causing rotational resonance.

[0008]

FIG. 1 is a perspective view showing a base mechanism 1 in a CD-ROM drive device, which is an embodiment in which the present invention is applied to a spindle motor for driving a turntable on which a disc is mounted in a CD-ROM drive device. 1 will be described. The turntable 2 that supports a disk (not shown) on which information is recorded so that the linear velocity is constant has a cone-shaped circular convex portion 3 that is engaged with the center hole of the disk and a circular shape that mounts the disk. And the mounting surface 4 thereof. The turntable 2 is fixed to a rotary shaft 7 of a main motor 6 fixed to the chassis 5.

A pinion gear 11 is fixed to the lower surface of the turntable 2, and the pinion gear 11 meshes with a large-diameter gear 13 pivotally supported by a shaft 12 provided on the chassis 5. Small diameter gear 1 integrally molded with large diameter gear 13
Reference numeral 4 meshes with a pinion gear 17 provided on the rotary shaft 16 of the sub motor 15. Here, the main motor 6,
The sub motors 15 are the same general-purpose DC brush motors, and have the same outer diameter and characteristics.

Here, the rotary shaft 7 of the main motor 6 and the rotary shaft 16 of the sub motor 15 are connected by a connecting gear mechanism 10 including a pinion gear 11, a large diameter gear 13, a small diameter gear 14 and a pinion gear 17 in a ratio of 1: 2. They are connected at a gear ratio of 5, and when the rotary shaft 7 makes one rotation, the rotary shaft 16 becomes 0.4
It is connected to rotate. Also, the pinion gear 11
A rotary disc 18 having a large number of slits formed therein is fixed, and the number of revolutions of the disc is detected by a photocoupler 19 arranged so as to sandwich the rotary disc 18.
For the sake of explanation, the turntable 2 and the connecting gear mechanism 10 are shown in an expanded state from their respective axially supported states.

Two guide shafts 21 and 22 extending in parallel are fixedly arranged on the chassis 5, and an optical pickup 24 having an objective lens 23 is movably supported along the guide shafts 21 and 22. A rack gear 25 extending parallel to the moving direction of the optical pickup 24 is fixed to the optical pickup 24, and the rack gear 25 meshes with a small-diameter gear 26 axially supported by the chassis 5. A large-diameter gear 27 integrally formed with the small-diameter gear 26 is meshed with a pinion gear 31 fixed to a rotation shaft of a thread motor 30 via a gear 28 pivotally supported by the chassis 5.

The large-diameter gear 27 is also meshed with a gear 32 pivotally supported by the chassis 5, and a rotary disc 33 having a large number of slits is fixed to the gear 32.
The photocoupler 34 is arranged so as to sandwich the rotating disc 33, and detects the movement of the optical pickup 24.

FIG. 2 is a block diagram showing a drive circuit for the motors 6 and 15. Based on the reproduction signal from the optical pickup 24, the control circuit 50 outputs a spindle motor drive signal to its output terminal 51. This signal is output to the main motor 6 via the amplifier 52, and the resistance 53,
It is output to the sub motor 15 via the amplifier 54. One contact of the switch 55 is connected to the connection point of the resistor 53 and the amplifier 54, and the other contact is connected to one end of the resistor 56. The other end of the resistor 56 is connected to the ground. The switch 55 is controlled to be closed during reproduction of the disc and opened during access for moving the optical pickup 24 in the radial direction of the disc in order to change the reading position of the disc by the optical pickup 24. The photocoupler 19 is connected to the input terminal 57 of the control circuit 50 so that the rotation speed of the disk can be detected.

Here, when the switch 55 is closed, the resistors 53 and 56 form a voltage dividing circuit, and the voltage applied to the sub motor 15 with respect to the voltage applied to the main motor 6 is 1: 0. The ratio is 3.

At the time of reproducing the disc, the discs may be rotated at a predetermined rotation speed according to the reading position of the optical pickup 24.
The motor torque required for 5 is small. Therefore, at the time of this reproduction, the switch 55 is closed, so that the ratio of the voltages applied to both the motors 6 and 15 by the resistors 53 and 56 is 1: 0.3.
Both the motors 6 and 15 are driven so that the rotational speeds of the two motors differ from each other. Therefore, the backlash of the connecting gear mechanism 10 is removed, and the turntable 2 can be smoothly rotated and driven without generating unnecessary vibration or noise.

Further, when the disc is reproduced, the rotation speeds of the two motors 6 and 15 are different from each other at a ratio of 1: 0.4, so that resonance caused by the same rotation of the two motors 6 and 15 can be avoided. As a result, Disk vibration is reduced. FIG.
Shows a spectrum analysis diagram of a tracking error signal at the time of reproducing a disk, a solid line shows an apparatus of the embodiment, and a dotted line shows an apparatus in which the rotation shafts of both motors 6 and 15 are connected by gears so as to be 1: 1. From this figure, it can be seen that the tracking error signal is lowered particularly in the range of about 100 Hz to 600 Hz in the apparatus of this embodiment, and the vibration of the disk is lowered over this frequency range. In addition,
One scale on the vertical axis in FIG. 3 is 10 dB, especially 30
There is an improvement of about 10 dB near 0 Hz.

When the optical pickup 24 is moved in the radial direction of the disc in order to change the reading position of the disc by the optical pickup 24, the reading position in the radial direction of the disc is changed to rotate the disc as required. The speed must change rapidly. For example, when the reading position changes from the outer circumference to the inner circumference of the disc, it is necessary to increase the rotation speed of the disc. Therefore, at the time of this access,
When the switch 55 is opened, the same voltage is applied to both motors 6 and 15 so that the maximum torque is generated, and the rotation speed of the disk is accelerated with a sufficient torque by both motors 6 and 15.

Further, when the reading position is changed from the inner circumference to the outer circumference of the disk, the polarity of the drive voltage output from the terminal 51 is opposite to that at the time of acceleration, so that the rotation speeds of both motors 6 and 15 are rapidly increased. Will be decelerated to.

In the above-mentioned embodiment, the two motors are connected by the connecting gear, but the present invention is not limited to this, and the two motors do not have a large play and always rotate in synchronization. Any connecting member such as a possible timing belt can be applied. Further, the number of motors is not limited to two, and three or more motors may be provided as needed.

Further, the ratio of the voltages applied to the plurality of motors can be arbitrarily set depending on the connection ratio of the plurality of motors by the connecting mechanism and other factors, and the voltage ratio can be divided as in this embodiment. Besides setting by the circuit, it is also possible to set by other circuit means.

Furthermore, in the above-described embodiment, the present invention is described by being applied to the spindle motor for driving the disk rotation in the CD-ROM drive device, but the present invention is not limited to this, and other embodiments are possible. Of course, it can be applied to a motor for driving a driven body.

[0022]

According to the present invention, since a plurality of motors are provided and these motor shafts are connected by the connecting members so that the rotation ratios thereof are different, it becomes possible to obtain the required torque with a plurality of inexpensive motors. Since it is possible to reduce unnecessary vibration caused by rotating a plurality of motors at the same time and smoothly rotate the driven body, it is possible to provide a high-performance motor with a small cost increase.

[Brief description of drawings]

FIG. 1 is a perspective view showing a base mechanism 1 in a CD-ROM drive device to which the present invention is applied.

FIG. 2 is a block diagram showing a motor drive circuit.

FIG. 3 is a spectrum analysis diagram of a tracking error signal.

[Explanation of symbols]

 1 base mechanism 2 turntable 5 chassis 6 main motor 7 rotating shaft 10 connecting gear mechanism 15 sub-motor 16 rotating shaft 24 optical pickup 50 control circuit 55 switch

Claims (4)

[Claims] 1. A composite motor comprising: a plurality of motors for driving a driven body; and a connecting means for connecting respective rotation shafts of the plurality of motors so that their rotation ratios are different from each other. 2. The composite motor according to claim 1, wherein the plurality of motors are DC motors having substantially the same characteristics. 3. The composite motor according to claim 1, wherein a rotary shaft of any one of the plurality of motors is used as an output shaft. 4. The composite motor according to claim 1, wherein the composite motor is a spindle motor that rotates a disk on which information is recorded.