JPH0260449A - Motor for media driving gear - Google Patents

Abstract

PURPOSE:To reduce the number of components and manhours for assembly work and to cut down the cost required by projecting an index magnet from the circumference of an FG magnet and by providing an index sensor to the surface of a printed circuit board in a surface mounting manner corresponding to the index magnet. CONSTITUTION:An FG magnet 9 is worn over the open periphery of a rotor yoke 6. An index magnet 10 is projected from the outer periphery of this FG magnet 9. Both magnets 9 and 10 are integrally moulded, and that magnetized in the axial direction of a motor. A printed circuit board 11 is installed to the surface of the rotor yoke 6 side of a housing 1. An index sensor 14 to sense the index magnet 10 is provided to the surface to the printed circuit board 11 in a surface mounting manner. In every rotation of a rotor 3 an index sensor 14 is induced to the index magnet 10 integrally moulded to the FG magnet 9 and senses the index magnet 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motor for a media drive device that rotationally drives a media such as a floppy disk.

[Conventional technology]

In a motor that rotates a floppy disk, the rotation of the motor is detected as a frequency in order to maintain a constant rotation speed, and the speed is controlled based on the frequency. For this purpose, conventionally, a ring-shaped FG magnet magnetized in the axial direction of the motor was attached to the rotor yoke of the rotor, and the FG magnet was attached to a printed circuit board attached to the housing that rotatably supported the rotor. Opposing FG detection circuit patterns are provided. With this FG detection structure, a voltage having a frequency of 172, which is the number of poles of the rotor magnet, can be generated every time the rotor rotates once.

In addition, in the motor that rotates the floppy disk, an index signal is obtained which serves as a reference for writing and reading from and to the floppy disk, in addition to the FG detection structure. For this reason, in conventional motors, an index magnet magnetized in the radial direction of the rotor is fixed to the outer peripheral surface of the rotor yoke with adhesive, and an index sensor for detecting this magnet is mounted on a printed circuit board. The surface of the index magnet facing the sensor has a single pole.

The index sensor has its terminal legs bent into an L shape, soldered onto a printed circuit board, and fixed with adhesive from above. It was placed opposite the outer circumferential surface of the With this index detection structure, the index magnet faces the index sensor every time the rotor rotates once, so the sensor can respond and output a detection signal for obtaining an index signal.

[Invention or problem to be solved]

However, in the conventional configuration as described above, since the FG magnet and the index magnet are required separately, there is a problem that the number of parts is large and that the parts must be individually attached to the rotor yoke.

Moreover, mounting the index sensor vertically on the printed circuit board requires manual soldering while maintaining its vertical position, which is time consuming and therefore costly. In addition, since the index sensor is installed manually as described above, it is difficult to accurately determine the position of the sensor.
There is a problem in that the gap between the sensor and the index magnet tends to vary from motor to motor, making it difficult to output a detection signal at a stable timing.

Furthermore, as conventional index magnets are magnetized in the radial direction as mentioned above, and the surface facing the index sensor has a single pole, the rise position of the index sensor's half-wave output waveform is clear. Not. Therefore, when processing is performed to obtain an index signal by shaping the output waveform, the rising position of the resulting square wave (index signal) tends to vary. Therefore, there is a problem that the accuracy of the index signal is not good.

The object of the present invention is to provide a motor for a media drive device that not only can reduce the number of parts and assembly man-hours and can be obtained at low cost, but also can output an index signal with stable timing, and further improves the accuracy of the index signal. The purpose of the present invention is to provide a motor for a media drive device that can perform the following functions.

[Failure to solve the problem]

In order to achieve the above object, in the motor for a media drive device of the present invention, an FG is attached to the rotor yoke.
An index magnet is made to protrude from the circumferential surface of the magnet, and both magnets are integrally molded, and both magnets are magnetized in the axial direction of the motor, and an index sensor that detects the index magnet is made to correspond to the index magnet. It is surface mounted on the surface of a printed circuit board.

Further, in order to improve the accuracy of the index signal, it is preferable to magnetize the index magnet integrated with the FG magnet into two poles, and to divide the index magnet into two in the circumferential direction and provide these magnetic poles adjacent to each other.

[Effect]

In the media drive unit configured as described above, the FG magnet and the index magnet are integrally molded, so that the number of parts and the effort for installation can be reduced. Since both of these magnets are magnetized in the axial direction of the motor, they can be magnetized at the same time and do not magnetically interfere with each other.

Additionally, by adopting an index magnet that is magnetized in the axial direction of the motor, a surface-mount type index sensor can be used to detect this.

This allows automatic surface mounting, commonly known as a chip mounter.
A surface-mount type index sensor can be automatically set in a predetermined position on a printed circuit board using a mounting device, and the sensor can be automatically soldered in the predetermined position by a subsequent heating process. That is, the index magnet can be surface-mounted automatically and accurately at a predetermined position without manual work. Therefore, the gap between the index magnet and the index sensor can be managed uniformly.

In addition, in a media drive motor equipped with a two-pole magnetized index magnet, a surface-mounted index sensor detects the index magnet every time the rotor rotates once and outputs a sinusoidal detection signal. do. This signal is waveform-shaped to become an index signal consisting of a square wave, but the point in time when it passes through the 0 volt level coincides with the rising or falling portion of the square wave, and this point also extends from the generation of the sine wave to its disappearance. Since this is exactly 1/2 of the time required for the index signal, the accuracy of the index signal can be improved.

〔Example〕

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

Reference numeral 1 in FIG. 1 denotes a housing, and a rotating shaft 4 of a rotor 3 is rotatably supported in the center of the housing through a bearing 2.

The rotor 3 has a rotor bushing 5 attached to the lower end of the rotating shaft 4 passing through the housing 1 in FIG.
It is formed by attaching a rotor magnet 7 to the inner surface of a rotor yoke 6. Further, in FIG. 1, a media holding stand 8 is attached to the second end of the rotating shaft 4. This holding table 8 is adapted to removably hold a medium (not shown) such as a 3.5-inch floppy disk, for example.

A ring-shaped FG magnet 9 is attached to the opening edge of the shallow dish-shaped rotor yoke 6 via an adhesive so as to cover the edge. An index magnet 10 is protruded from the outer peripheral surface of the FG magnet 9, as shown in FIGS. 1 and 2. Both magnets 9 and 10 are integrally molded from a so-called plastic magnet made by mixing magnetic powder into plastic. Furthermore, both magnets 9°]-0 are magnetized in the axial direction of the motor, and the magnetization is performed simultaneously.゛'' By the magnetization described in 1.
As shown in FIG. 2, the G magnet 9 has alternating S and N poles occupying a predetermined area, and the index magnet [0] has adjacent S and N poles of the FG magnet 9. The poles are integrally extended radially outward. That is, the index magnet 10 is magnetized into two poles as shown in FIG. 2, and these magnetic poles divide the index magnet 10 into two in the circumferential direction and are adjacent to each other. Moreover, the index magnet 10 is provided further away from the printed circuit board 11, which will be described later, than the FG magnet 9, as shown in FIG.

Further, a printed circuit board 11 is attached to the surface of the housing on the rotor yoke 6 side. A plurality of drive coils 12 are attached to the circuit board 1 facing the rotor magnet 7, and electronic circuit components for motor drive and speed control are located outside the rotor yoke 6]
-3 is installed.

Furthermore, an FG detection circuit pattern (not shown) is provided on the printed circuit board 11 facing the FG magnet 9. Furthermore, a surface-mounted index sensor 14 for detecting the index magnet 10 is mounted on the printed circuit board 11 near the outside of the rotor yoke 6.

The direction of magnetic sensitivity of this sensor 14 is the axial direction of the motor,
That is, in the vertical direction in FIG.

Note that surface mounting means that a solder agent, commonly known as cream solder, is applied to the specified position of the printed circuit board in advance, and a surface mount component formed in the form of a chip is set on top of the solder agent, and then heated. This is a technique that simultaneously electrically connects and mechanically fixes the surface-mounted component to the printed circuit board via the solder agent by performing heat treatment in a furnace.

In the motor configured as described above, in addition to detecting the rotational position of the rotor 3 by a position detection sensor (not shown) attached to the printed circuit board 11, the excitation of each drive coil 2 is controlled by the drive electronic circuit components. As a result, the rotor 3 can be rotationally driven by the magnetic attraction effect formed between the magnetic force generated in the drive coil 12 and the magnetic force of the rotor magnet 7.

As the rotor 3 rotates, the FG magnet 9 is connected to the FG detection circuit pattern provided on the printed circuit board 1.
The position of F changes each time the rotor 3 rotates once.
A voltage (F
The above-mentioned detection pattern generates a signal multiplied by G. Since this FG multiplied signal is input to a speed control circuit (not shown), this circuit controls the rotational speed of the rotor 3 to be kept constant.

The rotor 3 rotated at a constant speed as described above is
After one rotation, the index magnet 10 integrated with the FG magnet faces the index sensor 14. At this time, the index sensor 14 senses and detects the index magnet 10. This signal is waveform-shaped by a waveform shaping circuit (not shown) to become an index signal consisting of a square wave, and based on this signal, only information is written to or read from the medium rotated together with the rotor 3.

By the way, since the index magnet 10 is magnetized with two poles, the index sensor 1 that detects this
4 outputs a detection signal of a sine wave A shown in FIG. Since this signal is a sine wave A, the sine wave A crosses the 0 halt level at time t2, which is exactly 1/2 of the time required from generation time t1 to extinction time t3. Further, the waveform shaping circuit (not shown) shapes the waveform of the latter half wave portion of the sine wave A. The resulting index signal B consisting of a square wave is shown in FIG. The rising edge of signal B is formed at the time t2 and is used as a reference for the index, so that the accuracy of the index signal is improved.

Furthermore, in the second motor configuration, since the FG magnet 9 and the index magnet 10 are integrally molded, the number of parts and the effort of installation can be reduced. Since the index magnet 10 is magnetized in the axial direction of the motor, by employing this magnet 10, it is possible to use a surface mount type index sensor 14 for detecting the index magnet 10. As a result, an automatic imposition device commonly known as a chip mounter can be used to automatically mount and set the surface-mount type index sensor 14 on a predetermined position on the printed circuit board 11, and then heat the index sensor 14. 4 can be soldered at the above predetermined position.

That is, the index sensor 14 can be surface-mounted automatically and accurately at a predetermined position without manual work. Therefore, cost reduction can be achieved by the above.

At the same time, the accuracy of mounting the index sensor 14 and index magnet 10 is increased, so
The gap between these index magnets 10 and index sensors 14 can be managed uniformly. Therefore, the index signal can be generated at stable timing.

As in the second embodiment shown in FIGS. 5 and 6, the present invention has a protective flange portion 9a on the outer peripheral surface of the FG magnet 9.
may be integrally provided. The flange portion 9a has a protrusion length equal to or greater than the protrusion length of the index magnet 10, is thinner than the thickness of the index magnet 10, and is formed at a distance from the index sensor ]4 than the index magnet 10. has been done. It should be noted that the above-mentioned unintended configuration is the same as that of the first embodiment, including the parts not shown.

According to the second embodiment, not only can the intended purpose of the present invention be achieved, but also the flange prevents work tools from colliding with the index magnet 10 during assembly, inspection, adjustment, etc. 3. The magnet 10 can be protected by preventing this by the portion 9a. Note that, depending on the position and thickness of the flange portion 9a, the index sensor 4 will not malfunction due to its magnetic force.

As shown in the third embodiment shown in FIGS. 7 and 8, the present invention provides a protective flange portion 9a on the outer peripheral surface of the FG magnet 9 to achieve the same effect as the second embodiment. At the same time, a cover portion 6a that covers the index magnet 10 may be integrally formed on the rotor yoke 6. Note that the configuration other than the following two points is the same as that of the first embodiment, including parts not shown.

According to the third embodiment, not only can the desired objective 1 of the present invention be achieved, but also the leakage of magnetic flux to the outside of the index magnet 10 can be reduced because the cover part 6a serves as a back yoke. can.

(7) Therefore, the magnetic flux acting on the index sensor 14 increases, and the index sensor 14 can be operated with higher reliability.

As shown in the fourth embodiment shown in FIGS. 9 and 10, the present invention provides an FG magnet 9 and an index magnet]
Simultaneously with the molding of magnets 9 and 10, a portion of the plastic magnet that is the molding material for both magnets 9 and 10 is filled into the tapered hole 6b provided in the rotor yoke 6, which is set in advance in the mold (note that 9b is a part of the plastic magnet). The rotor yoke 6 and the plastic magnet are integrated, and the rotor yoke 6 is made of a Hita plate structure, and the protective flange 9a and the index magnet 10 are covered with the periphery of the rotor yoke 6. Good too. In addition,
The configuration other than the above points, including parts not shown, is the same as described in 1 above.
It is similar to that of the example.

According to the fourth embodiment, not only can the intended purpose of the present invention be achieved, but also there is no need to attach the plastic magnet to the rotor yoke 6 with adhesive, which further reduces the number of installation steps and costs. Since the gap can be further reduced and the positional accuracy of the plastic magnet is improved, the gap between the index magnet 10 and the index sensor 14 can be managed more uniformly.

As shown in the fifth embodiment shown in FIG. 11, the index magnet 10 may be integrally provided on the inner circumferential surface of the FG magnet 9. Note that the configuration other than the above points is the same as that of the first embodiment, including parts not shown.

According to such a fifth embodiment, not only can the intended purpose of the present invention be achieved, but also the index magnet] 0 can be operated at the time of assembly, inspection, adjustment, etc. as in the second embodiment. This magnet 10 can be protected since it will not be hit by tools or the like.

Note that the present invention can also be applied to a radial gap type motor for a media drive device. In addition, if an iron plate PC board is used for printed circuit board] 1, index sensor]
The reaction in step 4 can be made better.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

]7 In the motor of claim 1, the index magnet is made to protrude from the circumferential surface of the FG magnet attached to the rotor yoke, and both of these magnets are integrally molded, and both of these magnets are magnetized in the axial direction of the motor,
In addition, by surface-mounting the index sensor that detects the index magnet on the surface of the printed circuit board in correspondence with the index magnet, the number of parts and assembly man-hours can be reduced, and it can be obtained at low cost and is stable. The index signal can be output at the same timing.

Further, in the motor of claim 2, the index magnet integrated with the FG magnet is magnetized into two poles, and these magnetic poles are divided into two in the circumferential direction and provided adjacent to each other, so that the index The accuracy of the signal can be improved.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention, FIG. 1 is a vertical sectional side view of the entire motor, FIG. 2 is a plan view showing a part of the FG magnet, and FIG. 3 is an index. FIG. 4 is a waveform diagram obtained by shaping the waveform shown in FIG. 3. FIG. 5 is a bottom view of a part of the rotor used in the second embodiment of the present invention, and FIG. 6 is a sectional view taken along the line X--X in FIG. 9. FIG. 7 is a bottom view of a part of the rotor used in the third embodiment of the present invention, and FIG. 8 is a sectional view taken along line X--X in FIG. 9. FIG. 9 is a bottom view of a part of the rotor used in the fourth embodiment of the present invention, and FIG.
The figure is a sectional view taken along the line XX in FIG. 9. FIG. 11 is a back view of the rotor yoke used in the rotor shown in the fifth embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Housing, 3... Rotor, 6... Rotor yoke, 9... FG magnet, 10... Index magnet, 11... Printed circuit board, 14... Index sensor applicant's attorney, patent attorney Takehiko Suzue

Claims (2)

[Claims] (1) A housing that rotatably supports the rotor is attached to a printed circuit board, an index magnet is attached to the rotor yoke of the rotor, and an index sensor for detecting this magnet is attached to the printed circuit board and attached to the rotor yoke. An FG magnet and an FG provided on the printed circuit board opposite to the FG magnet.
In a motor for a media drive device that detects the rotation speed of the rotor using a detection circuit pattern, the index magnet is made to protrude from the circumferential surface of the FG magnet, and both of these magnets are integrally molded. A motor for a media drive device, characterized in that the motor is magnetized in the axial direction of the motor, and the index sensor is surface-mounted on the surface of the printed circuit board in correspondence with the index magnet. (2) The above index magnet is magnetized into two poles,
2. The motor for a media drive device according to claim 1, wherein these magnetic poles divide the index magnet into two in the circumferential direction and are adjacent to each other.