JPH04134178U - Motor pulse signal generator - Google Patents

Abstract

(57) [Summary] [Purpose] A motor pulse that can output a pulse signal with a good S/N ratio that has a steep slope at the threshold level and a sufficient peak value with respect to the reference level. Providing signal generators. [Structure] The pulse generating magnetic pole pieces arranged on the peripheral surface of the rotor yoke of the motor are polarized into two poles, an S pole and an N pole along the rotation direction of the rotor yoke, and the area of the S pole region and the N pole are polarized. This is a pulse signal generating device for a motor in which regions are formed with different areas and a magnetic detection element is fixedly arranged on the stator side facing the pulse generating magnetic pole piece.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a pulse signal generator for a motor, such as a microfloppy disk. A pulse signal generator suitable for use in a brushless motor that rotates a motor Regarding improvements.

0002

[Conventional technology]

Conventionally, this type of pulse signal generator has a stator as shown in FIG. 5A. A side wall (not shown) of a cup-shaped rotor yoke (1) rotatably supported 3), a pulse generating magnetic pole piece (5) is arranged on the side wall (3) of this rotor yoke (1). ) A configuration in which a magnetic detection element (7) such as a Hall element is fixedly arranged on the stator side. It has been known.

0003 This pulse generating magnetic pole piece (5) has a chip attached to the side wall (3) of the rotor yoke (1). A drive magnet with shaped magnetic pole pieces attached or fixed inside the rotor yoke (1). A part of the cut (not shown) is made to protrude from a notch formed in the side wall (3). As shown in the figure, for example, the magnet is unipolarized so that the N pole is exposed.

0004 In such a pulse signal generator for a motor, single-pole magnetization is used as shown in Figure 5B. When the rotor yoke (1) rotates, the pulse generating magnetic pole piece (5) becomes magnetic. Each time it approaches or passes the detection element (7), a single peak pulse signal as shown in Fig. 5C is generated. is obtained from the magnetic detection element (7).

[0005] Then, with respect to the pulse signal from the magnetic detection element (7), for example, there is a pulse signal on the positive side. The timing when the threshold level Th is exceeded is detected, and this timing signal is is used as an index signal for the microfloppy disk drive. .

[0006] However, due to changes in ambient temperature, etc., the magnetic detection element (7) as shown in Figure 5C The peak value of the pulse waveform may change slightly. This allows the index However, there is a drawback in that a slight deviation occurs in the timing of the signal.

[0007] In order to keep this deviation as small as possible, it is necessary to It is necessary to make the slope of the pulse waveform extremely steep.

[0008] The conventional example shown in Fig. 6A was improved by focusing on this point, and the rotor yaw The pulse generating magnetic pole piece (5) disposed on the side wall (3) of the block (1) is shown in FIG. 6B. The rotor yoke (1) is polarized equally into S and N poles along the rotational direction. This is what is being done.

[0009] In this case, as the rotor yoke (1) rotates, the vicinity of the magnetic detection element (7) is When the magnetic pole piece (5) for generating a magnetic flux approaches or passes, it is obtained from the magnetic detection element (7). The pulse signal has a pulse waveform with two extreme values, high and low, as shown in Figure 6C. . The waveform between these two extreme values is an abrupt change from the S pole to the N pole of the pulse generating magnetic pole piece (5). This is the part where drastic changes in magnetic flux are being detected, so it is very steep. Okay By setting the threshold level Th within this range, the ambient temperature It is possible to obtain an index signal with good characteristics that is stable against changes etc. .

0010

[Problem that the idea aims to solve]

However, in the pulse signal generator of FIG. 6 described above, the magnetic detection element (7) If the peak value of the pulse signal obtained from the There is a drawback. This is the signal-to-noise ratio of the pulse signal obtained from the magnetic detection element (7). This means that the sound ratio (hereinafter referred to as S/N ratio) is not good, and the index signal The circuit operation that produces this lacks stability.

[0011] In addition, in order to increase the peak value, the magnetic force of the pulse generating magnetic pole piece (5) must be strengthened. However, if the pulse signal generator is a microfloppy disk drive, etc. Because floppy disks are magnetic recording media, when used in It is necessary to minimize the magnetic flux leaking to the pulse generating magnetic pole piece (5). There are limits to making it stronger, and it is not practical.

0012 This invention was devised to solve these conventional drawbacks, and The slope at hold level Th is steep and the wave height value is sufficient for the reference level. A motor pulse signal generator capable of generating pulse signals with a good S/N ratio. The purpose is to provide.

[0013]

[Means to solve the problem]

In order to solve these problems, the present invention has a structure that is rotatably supported on the stator side. A magnetic pole piece for pulse generation is arranged on the peripheral surface of the rotor yoke, and this magnetic pole piece for pulse generation A magnetic sensing element is placed on the stator toward the pole piece, and the pulse generating magnetic pole piece is placed on the stator. The motor yoke is polarized into two poles, an S pole and a N pole, along the rotation direction, and the S pole region is The area of the region and the area of the N-pole region are different from each other.

[0014]

[Effect]

In the present invention equipped with such a means, the pulse generating magnetic pole piece is bipolarly magnetized. Therefore, whether the magnetic detection element detects a sudden change in magnetic flux near the boundary of the magnetic poles As a result, the slope of the output pulse waveform becomes steep. Furthermore, the reference level of the pulse signal The area of the magnetic pole that derives the waveform that is actually used is the area of the other magnetic pole. If it is formed wider than the region area, a sufficiently high wave height value can be obtained and the S/N ratio will be good. Ru.

[0015]

【Example】

Embodiments of the present invention will be described below with reference to the drawings. Note that the parts common to the conventional example are given the same symbols.

[0016] FIG. 1 is a schematic plan view showing an embodiment of a motor pulse signal generator according to the present invention. Figure 2 shows a brushless motor equipped with the pulse signal generator according to the present invention. FIG. For convenience, explanation will be given starting from FIG.

[0017] In FIG. 2, the hollow cylindrical bearing housing (9) has bearing portions at both end openings. A pair of ball bearings (12) and (13) are fixed coaxially, and the shaft A circuit board (15) is fitted onto the flange formed on the outer periphery of the receiving housing (9). It is fixed in such a way that This circuit board (15) is provided with printed wiring, etc. A fixed circuit pattern (not shown) is formed.

[0018] A plurality of sheets are placed on this circuit board (15) via a ring-shaped spacer plate (23). A magnetic core (17) made of laminated magnetic steel plates is fixed. This magnetic core (17) has multiple salient pole teeth that protrude radially in the radial direction, and these salient pole teeth have multiple The phase drive coil (19) is wound in sections, and the terminal is located at the circuit board (15). connected to a fixed circuit pattern.

[0019] A rotary shaft (21) is rotatably supported by the ball bearings (12) and (13). The rotating shaft (21) has a cup-shaped rotor at one end as shown in the figure. The yoke (1) is fixed with screws (25). And this rotor yoke (1 ) A ring-shaped driving magnet (27) is fixed inside the side wall (3) of the It is arranged so as to face the outer periphery of the core (17) with a slight interval therebetween.

[0020] As shown in Figure 1, the outer periphery of the side wall (3) of the rotor yoke (1) is equipped with a pulse generation magnet. A pole piece (5) is attached. This pulse generating magnetic pole piece (5) is (1) is polarized into two poles, an N pole and an S pole, along the rotation direction, and the area of the N pole area is is formed to be larger than the area of the S pole region.

[0021] On the circuit board (15), a magnetic detection element (7) using a Hall element generates pulses. The magnetic pole pieces (5) are arranged to face the magnetic pole piece (5), and as the rotor yoke (1) rotates. Every time the pulse generating magnetic pole piece (5) approaches or passes, it outputs a pulse signal, which will be described later. . In addition, in Fig. 2, there is a notch (3a) in a part of the side wall (3) of the rotor yoke (1). A pulse generating magnetic pole piece (5) is housed and fixed in this notch (3a). The structure is shown. By doing this, the pulse generation magnetic pole piece (5) The pasting position becomes clear and the pasting strength is also ensured sufficiently. Also, illustrated Although it is not done, a part of the outer periphery of the drive magnet (27) is formed to protrude and the rotor yaw is The magnetic pole piece for pulse generation is exposed through the notch (3a) of the pole piece (1) and magnetized. You can also use it as

[0022] In addition, the symbol (29) in Fig. 2 is a turntable fixed to the rotating shaft (21). be.

[0023] The motor pulse signal generator of the present invention is suitable for brushless motors. The rotor yoke (1) rotates by switching the drive coil (19) and energizing it. The pulse generation magnetic pole piece (5) passes near the magnetic detection element (7), and the pulse Outputs a pulse signal.

[0024] A magnetic pole for pulse generation in which the N-pole region is magnetized wider than the S-pole region as shown in Figure 3A. The piece (5) approaches the magnetic detection element (7) from the north pole side, and when it passes, it generates a magnetic field. The output pulse waveform obtained from the air detection element (7) is as shown in FIG. 3B. As shown in the diagram The pulse waveform of this sea urchin is based on the N of the magnetic pole piece (5) for pulse generation to the magnetic detection element (7). As the poles approach, the N pole rises relatively slowly from the reference level, and a wide range of N poles rises. During the passage, a sufficient level of wave height is obtained, and then as the wave passes near the boundary with the S pole, When it falls sharply and falls slightly below the reference level, and the S pole has completely passed through, it is magnetic. The no-input level of magnetic flux to the detection element (7), that is, the return to the reference level. It is.

[0025] By utilizing the steep gradient between the maximum and minimum of the pulse waveform in Figure 3B, To obtain the index signal of a floppy disk drive, for example, a conventional well-known system is used. A certain threshold level above the reference level is The second threshold level is set near the reference level. Obtain a signal that rises at bell Th2, and at the timing of the rise of this signal In response, a signal falling as shown in FIG. 3C is output from a well-known logic circuit, If this falling edge in Figure 3C is used as an index signal, the microflop This ensures stable and good operation of the disk drive.

[0026] FIG. 4 is a diagram for explaining the operation of another embodiment of the present invention, and FIG. 4A is a diagram for explaining the operation of another embodiment of the present invention. It is a figure which shows the magnetized state of a magnetic pole piece (5). In this example, the south pole region is larger than the north pole region. Magnetization is applied so that the magnetic field is widened, and the magnetic detection element (7) is first from the magnetic detection element (7) as the wide S-pole region passes by. The output pulse waveform is shown in FIG. 4B. In this case, the difference should be sufficiently higher than the reference level. The threshold level Th is set to the level of the well-known Schmitt trigger. Using a circuit or a monostable multivibrator, generate a pulse as shown in Figure 4C. A waveform is obtained and the falling edge of this pulse waveform is used as an index signal.

[0027]

[Effect of the idea]

As explained above, the present invention has bipolar magnetization at the N pole and S pole, and the N pole area surface. Since we used pulse generation magnetic pole pieces with different products and S-pole area areas, the steepness of the slope a pulse having a sufficient wave height to ensure a good signal-to-noise ratio. signal.

[0028] This pulse signal can also be used to load the microfloppy disk drive. By deriving the dex signal, the influence of ambient temperature changes and noise can be minimized. can be done.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing an embodiment of a motor pulse signal generator according to the present invention.

FIG. 2 is a longitudinal sectional view of a brushless motor equipped with the pulse signal generator of FIG. 1;

FIG. 3 is a diagram illustrating the operation of the pulse signal generator shown in FIG. 1;

FIG. 4 is a diagram illustrating the operation of another embodiment of the present invention.

FIG. 5 is a schematic plan view of a conventional pulse signal generator for a motor and a diagram illustrating its operation.

FIG. 6 is a schematic plan view showing another example of a conventional pulse signal generator for a motor and a diagram illustrating its operation.

[Explanation of symbols]

(1) Rotor yoke (3) Side wall (3a) Notch part (5) Magnetic pole piece for pulse generation (7) Magnetic detection element (9) Bearing housing (12) (13) Ball bearing (17) Magnetic core (19) Drive coil (21) Rotating axis (23) Spacer plate (25) Screw (27) Drive magnet (29) Turntable

Claims (1)

[Scope of utility model registration request] 1. A motor comprising: a magnetic pole piece for pulse generation disposed on the circumferential surface of a rotor yoke rotatably supported on the stator side; and a magnetic detection element disposed on the stator facing the magnetic pole piece for pulse generation. In the pulse signal generator, the pulse generating magnetic pole piece is polarized into two poles, a south pole and a north pole along the rotational direction of the rotor yoke, and the area of the south pole region and the area of the north pole region are made different. A pulse signal generator for a motor, characterized in that: