JPS61196776A - Drive circuit of polyphase direct drive motor - Google Patents

Abstract

PURPOSE:To perform a nonmechanical brake function having high reliability without noise by shortcircuiting at least two phases of exciting phases of a polyphase direct drive motor when a power source is turned OFF to stop the motor. CONSTITUTION:A relay 54a is opened at normal operation time, and the exciting currents of the phases of a DC motor are sequentially output from a DD motor speed controller 52 and a logic drive circuit 53 to an exciting coil 56 on the basis of a rotating pulse from a Hall IC 55k in the DD motor. When a power source is turned OFF, a relay 54a is closed to shortcircuit the two phases of the coil 56, and two of three phases are set to the same potential. Thus, a braking action due to an inertial rotation arises to rapidly stop a rotor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an information recording/reproducing device for recording and reproducing information on a disk-shaped recording medium, and more specifically, to a rotational drive of the disk-shaped recording medium. The present invention relates to a drive circuit for driving a direct drive motor that performs.

[Background of the invention]

As an example of a device using a disk-shaped recording medium, there is a magnetic recording/reproducing device as shown in FIGS. 4(a) and 4(b), which uses a particularly hard type magnetic disk.

A magnetic recording/reproducing device (hereinafter referred to as a magnetic disk device) as shown in the figure is a magnetic recording/reproducing device that records information on a magnetic disk.
a magnetic head 2 that records and reproduces information on the magnetic disk 1; a direct drive motor (hereinafter abbreviated as DD motor) 3 that rotationally drives the magnetic disk 1; A head drive mechanism 4 for moving to a predetermined track on the head 1, a base plate 5 serving as the base of a casing that houses the magnetic disk 1, the magnetic head 2, etc. and maintains it in a sealed state, a motor drive circuit, a control circuit, etc. It mainly consists of a printed circuit board 6 on which is formed, and a frame 7 for attaching the printed circuit board 6 to the base plate 5.

In this magnetic disk device, the magnetic disk 1 is
Two-layered magnetic heads 2 are used for double-sided recording on one magnetic disk 1. One magnetic head 2 is provided on each surface, four in total, and cantilevered on the swing arm 8 of the head drive mechanism 4. It is attached via a support spring. The head drive mechanism 4 consists of this swing arm 8, a steel belt 9 attached to a part of the swing arm 8, a pulley 10 around which the middle part of the steel belt 9 is wound, and a stepping motor 11. By inserting and fixing the pulley 10 around which the steel belt 9 is wound onto the drive shaft 12 of the stepping motor 11 and driving the stepping motor 11, the input wing arm 8 is swung around the rotational IP II 18a. It is possible.

Magnetic disk 1. Magnetic head 2. Swing arm 8.
The casing that houses the steel belt 9, pulley 10, etc. consists of the base plate 5 and a top cover (not shown).In order to maintain airtightness, there are no holes in the contact area between the base plate 5 and the top cover and the mounting area of the stepping motor 11. A gasket is used, and the shaft portion of the DD motor 3 is filled with magnetic fluid. Further, as shown in FIG. 4(b), an opening 5b is formed in a part of the base plate 5 in order to equalize the air pressure inside and outside the airtight chamber 5a. A filter (breather) 13 is provided to prevent dust from entering.

While the frame 7 is used for attachment to the outside, a base plate 5 is attached via a vibration isolating rubber 14, and the printed circuit board 6 is attached to the side opposite to the side where the base plate 5 is attached. A bezel 15 provided with a display device such as a louver or LED is also attached.

Further, a mechanical brake 16 is provided on the base plate 5 near the DD motor 3, and is intended to quickly stop the rotor of the DD motor 3 when the power is turned off. This brake 16 is an important element in the recording/reproducing method using the contact start/stop (hereinafter abbreviated as C8S) method in order to bring the magnetic head 2 to rest on the surface of the magnetic disk as quickly as possible. .

This is because the C8S method reduces the vertical load on the magnetic head 2, brings the magnetic head 2 into contact with the surface of the magnetic disk when the disk is not rotating, and when the magnetic disk 1 starts rotating, the rotation Therefore, when the rotation speed is below a predetermined number of rotations, the magnetic disk 1 cannot levitate, and when the magnetic disk 1 rotates at a rotation speed lower than the number of rotations at which levitation is not possible, the magnetic head 2 rotates while in contact with the surface of the magnetic disk 1, causing scratches on the surface of the magnetic disk 1, and there is a very high possibility that errors will occur due to the scratches. Therefore, 'c s
In the s-type magnetic disk device, the magnetic head 2
It is desirable that the time required from stopping to surfacing and from surfacing to stopping is as short as possible.

Conventionally, as mentioned above, the mechanical brake 16 was used to stop the DD motor (high-speed spindle motor) 3.
When the power is turned off, the brake 16 is brought into contact with the rotor of the DD motor 3, and the sliding (friction) resistance generated at this time stops the motor. The noise was loud and the product value was diminished. Since the specified rotational speed of the rotor is normally 3600 rpm, it is difficult to keep this operating noise low in relation to the stop time, which has been a problem. In addition, a lack of reliability due to wear of the brake shoes or brake pads used in the brake [6] has also been a problem.

[Purpose of the invention]

The present invention has been made in view of the above problems.

The purpose is to shorten the time it takes for the disk to stop rotating.
The object of the present invention is to propose a drive circuit for a DD motor for an information recording/reproducing device that is silent, highly reliable, and has a non-mechanical braking function.

[Summary of the invention]

In order to achieve the above object, the present invention short-circuits at least two of the excitation phases of the multiphase DD motor when the power is cut off in a drive circuit for a multiphase DD motor rotationally driven by a disk-shaped recording medium. It is characterized by a configuration in which a short circuit of the excitation phase causes the DD motor itself to perform a braking action, thereby stopping the DD motor and the disk 7 driven by it.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on the drawings.

1 to 3 are explanatory diagrams of a magnetic disk device according to an embodiment of the present invention, and FIG. 1 is a circuit diagram of a DD motor, and FIG.
This figure is a perspective view showing an outline of a magnetic disk drive not equipped with a mechanical brake, and FIG. 3 is an exploded perspective view showing the relationship between a DD motor and a magnetic disk driven by the DD motor. In the following description, the same or similar components as those of the conventional example shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIGS. 2 and 3, magnetic disk 1. A head drive mechanism 4 consisting of a swing arm 8 equipped with a magnetic head 2 and a pulley 10 around which a steel belt 9 is wound is housed in an airtight chamber 5a formed by a base plate 5. A stepping motor 11 and a DD motor 3 are mounted outside the airtight chamber 5a. The stepping motor 11 has the pulley 1 fitted on the drive shaft 12.
The swing arm 8 is driven to swing around the rotation axis 8a of the swing arm 8 via the shaft 8a.

The DD motor 3 uses a DC brushless type as shown in FIG. 19 are provided. A drive coil 20 is provided on the lower surface of this bracket 19, and a bearing 22 for rotatably holding a drive shaft 21 is fitted in the center of the drive coil 20. The peripheral surface 23 of the bracket 19 is fitted onto the lower surface of the base plate 5 without any gaps and is screwed. On the upper surface of this bracket 19, a drive hub 24. Two hard magnetic disks 1 are attached with a cap 26 via a spacer ring 25. Also.

A shallow groove 28 is formed on the upper surface of the bracket 19 and communicates with the flange opening 27 of the drive hub 24 .

The drive hub 24 has a cylindrical portion 29 and a flange portion 30 formed at a lower portion thereof, and a plurality of grooves 31 are formed in the axial direction of the outer peripheral surface of the cylindrical portion 29. This groove 31
continues from the top surface 32 of the cylindrical portion 29 to the lower surface of the flange portion 30 through the opening 27 provided in the flange portion 30, and on the upper surface of the flange portion 30, there is a recess 33 continuing from this groove portion 31 to the circumferential surface of the flange portion 30. It is a provision. Note that the cylindrical surface 34 of the cylindrical portion 29 excluding the groove 31 and the recess 3 of the flange portion 30
The upper surface 35 other than 3 serves as a reference for positioning the magnetic disk 1, and in order to rotate the magnetic disk 1 without eccentricity or wobbling. It is machined with high precision using the mounting surface 36 as a reference.

A plurality of notches 37 communicating with the inner and outer circumferences are formed on the end face of the spacer ring 25 sandwiched between the two magnetic disks 1, and are fitted into the cylindrical surface 34 of the drive hub 24. The cap 26 is formed into a substantially disk shape, has a plurality of grooves 38 formed on its lower surface that widen toward the outer circumference, is attached to the top surface 32 of the drive hub 24 with screws, and is attached to the magnetic disk 1 and the spacer. ring 2
5 is firmly attached to the upper surface 35 of the flange portion 30 of the drive hub 24.

In this way, the DD motor 3 is attached to the lower surface of the base plate 5, and the drive hub 24 is fitted to the drive shaft 21 of the DD motor 3.
The magnetic disk 1 is mounted on the outer peripheral surface of the magnetic disk 4, and the magnetic disk 1 can be rotated within the airtight chamber 5a.

A drive circuit for this DD motor 3 is shown in FIG.

The drive circuit consists of a power supply section 51, a DD motor speed control section 52, a logic drive section 53 that combines a logic section and a part of power, and a relay section 54, and is connected to each section of the DI) motor section 55. has been done.

The DD motor 3 uses a three-phase bipolar type, and the DD motor 555 has a three-phase excitation coil 56, Hall input terminals 55a, 55b, and Hall output terminal 55.
c+ 55d, 55e+ 55f.

55 g + 55 h, each with Hall IC
55i, 55j, and 55. A power supply section 51 that supplies power to the drive circuit is set to be able to apply voltages of 12V and 5V. The DDD motor speed control section 52 extracts the rotation speed from the Hall IC 55 of the DDD motor, obtains its pulse signal from the Hall output terminals 55g and 55h, and controls the [10 motor 3] using the IC 52a.
DD
A control signal for controlling the rotational speed of the D motor is input in the form of voltage to the control voltage input terminal 53a of the logic drive unit 53.

A logic drive section 53 consisting of an IC including a logic section and a power section takes out the rotation speed from the Hall ICs 55i+j and k, and also outputs the rotation speed from the control voltage input terminal 5'3a.
A speed control signal is obtained from the DD MOMO-555, and a drive current is sequentially sent to the excitation coil 56 of the DD MOMO-555.
It functions to keep the motor 3 at a specified rotation speed. 57
is a smoothing circuit for stabilizing the drive pulse of each excitation phase.

The relay part 54 is provided between the logic drive part 53 and the exciting coil 56 so that two phases out of the three phases of the exciting coil 56 of the DD momo-555 can be short-circuited, and during normal operation, the relay part 54 is
is always open, and when the power is turned off, a voltage of 12'V is applied to close the relay 54a.

With the above configuration, during normal operation, the relay 54a is open as described above, and the DDD motor uses the rotation pulse from the Hall IC 55k to send the excitation coil from the DD motor speed control section 52 to the logic drive circuit 53. 5
6, the excitation current of each phase is output in order, but when the power is turned off, the relay 54a closes and short-circuits the two phases of the excitation coil 56, making two of the three phases at the same potential. By using the electromotive force generated by the inertial rotation, a braking action can be caused to quickly stop the rotor 18. Therefore, the brake 16 that utilizes mechanical frictional force is unnecessary.

5 In this embodiment, a three-phase bipolar type Dr)
Although the description is given using a brushless DC motor as an example, it goes without saying that the present invention can be applied to any polyphase DDD motor.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a braking action is performed by shortening at least two of the multiphase excitation phases when the power is turned off using a relay.

■ Since there are no consumable parts such as friction parts like mechanical brakes, stable performance can be guaranteed over a long period of time.

(2) Regarding (2), since there is no friction part, there is no brake noise, and usability can be improved.

Since it is only necessary to insert a simple relay into the circuit, the cost is not only low, but also the manufacturing of the circuit device is easy because there is no need to make any special changes to the conventional circuit.

There are other effects.

[Brief explanation of drawings]

Figure 1 to 11g3r! ! 1 is a circuit diagram showing a drive circuit, FIG. 2 is a partially cutaway perspective view showing an overview of a magnetic disk device with the upper case removed, and 3 is a diagram J for explaining the present invention in detail. The figure is an exploded perspective view showing the relationship between the DDD motor magnetic disk, No. 41i! ! FIG. 4(a) is an exploded perspective view showing an overview of a conventional magnetic disk device, and FIG. 4(h) is a perspective view showing an overview of a filter (breather) section of the conventional magnetic disk device. l...Magnetic disk, 2...Magnetic head, 3...DDD motor 4...Head drive mechanism, 5...Pace plate, 8...
...Swinger 11.9...]...Steel belt, 10...Pulley, 11...Stepping motor, 1G...Mechanical brake,
17... Permanent magnet 218 Old... Rotor part, 1
9... Bracket, 20... Drive coil, 21... Drive shaft, 24... Drive hub, 25... Spacer ring, 26...
... Cap, 51 ... Power supply section, 52 ...
...Speed control section, 53...Logic drive section. 53a... Control voltage input terminal, 54...
... Relay part, 54a ... Relay, 55.
...Dr) Motor section, 55 i + 55 J
, 55 k... Hall element, 56...
Excitation coil. Procedural amendment band (voluntary) April 2, 1985

Claims (1)

[Claims] This is used in an information recording/reproducing device that records and reproduces information on a disk-shaped recording medium. Polyphase direct
1. A drive circuit for a polyphase direct drive motor, comprising short circuit means for shorting at least two of the excitation phases of the drive motor to stop the polyphase direct drive motor.