JPH0775374A - Rotation position detection circuit of electromagnetic rotary machine - Google Patents

Abstract

PURPOSE:To enable generation of rotation position signals from high-order AM modulation components even when included in rotation position detection signals by IPPr AM modulation of the intensity of a magnetic field formed between two electromagnetic coupled devices for detecting rotation speed. CONSTITUTION:An output Q1 of a D latch circuit 112 is inputted into a D latch circuit 114 which latches it by clock CLC to obtain an output Q2 shifted by the timing about half a clock cycle. The outputs Q1, Q2 of the D latch circuits 112, 114 are inputted into an AND circuit 115 to obtain an output (Q1+Q2). A D latch circuit 117 latches the output of the AND circuit 115, inputted into the data input terminal, by clock CLE obtained from clock CLD via a delay circuit 116. The rise timing of an output Q3 of this latch circuit 117 is used as a rotation position detection signal to trigger a time constant circuit 118 and outputted from as an index signal ID in a given delay time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic rotary machine such as a motor used in a floppy disk drive device, and more particularly to a rotary position detecting circuit for detecting the rotary position (index position) thereof.

[0002]

2. Description of the Related Art Conventionally, as a motor rotational position detecting device, a magnet is provided at a predetermined position of a rotating body of a motor,
At a fixed position of the stator facing this magnet,
2. Description of the Related Art There is known a rotational position detection device that detects a rotational position by obtaining a pulse signal using a magnetic detection element such as a Hall element that detects a magnetic change of a magnet.

FIG. 10 is a sectional view of a main part of a conventional three-phase brushless motor, and FIG. 11 is a sectional view taken along line XX of FIG. In such a conventional brushless motor, there are four magnetic circuits, namely, a magnetic circuit for generating a rotational driving force, a magnetic circuit for generating a rotation speed signal, a magnetic circuit for generating a rotation position signal, and a rotating magnetic field. A magnetic circuit for generating the excitation timing for generating the is formed.

First, referring to FIG. 11, a schematic structure of a three-phase brushless motor will be described. The substrate 7 is made of a magnetic material such as iron, and the oil-impregnated bearing 9 is press-fitted in the center thereof, while the outer peripheral end portion is a rotational position detecting means. The hall element 14 is provided. The rotary shaft 5 is connected to the rotor yoke 4 via a shaft fixing member 6.
It is integrated with. The oil-impregnated bearing 9 and the bearing 8 are fixed to the substrate 7, and the rotary shaft 5 is rotatably supported by the bearings 8 and 9. Therefore, the rotor yoke 4 integrated with the rotating shaft 5, the drive magnet 1, the speed detecting magnet 2 '(hereinafter, FG
The magnet 2 ′), the position detection magnet 13 and the like freely rotate with respect to the substrate 7.

A ring-shaped drive magnet 1 (FIG. 10) is fixed to the inner wall side of the outer edge of the rotor yoke 4 via a drive magnet yoke 3. As is well known, a rotating magnetic field is applied to the drive magnet 1 by the drive coil 10 to rotate the rotor yoke 4. For this reason, as shown in FIG. 10, the drive magnet 1 is circumferentially arranged with 16 poles along the outer edge of the rotor yoke 4, and each pole is magnetized in the radial direction. In order to apply a rotating magnetic field, a plurality of drive coils 10 are wound around a stator yoke 11 radially formed around the rotating shaft 5. In this way, the plurality of drive coils 10 provided in the circumferential direction on the yoke 11 are fixed on the iron substrate 7 by fixing members (not shown) such as screws.

In the above structure, the stator yoke 11
Together with the drive magnet 1, the rotor yoke 4, and the drive magnet yoke 3 form a closed magnetic circuit. In addition,
A brushless motor of the type in which the drive magnet 1 is provided so as to be separated from the yoke 11 in the radial direction of the stator yoke 11 is referred to as a circumferentially opposed motor or a radial gap motor.

A cutout 4 is formed on the outer peripheral surface of the rotor yoke 4.
h is formed, and the position detecting magnet 13 serving as the rotational position detecting means is embedded in the notch 4h. This magnet 13 also constitutes one magnetic circuit. Further, a plurality of Hall elements 12a, 12 for detecting the excitation timing of the coil 10 of each phase
b and 12c are fixed at appropriate positions on the substrate 7.
The magnetic field from the drive magnet 1 is applied to these Hall elements 12
a, 12b, 12c, so these Hall elements 1
A change in the magnetic field from the drive magnet 1 is detected by 2a, 12b, and 12c. The phase difference between the magnetic field to be generated by the coil 10 of the stator 11 and the magnetic field of the rotating drive magnet 1 is detected, and a current is applied to each phase of the drive coil at an appropriate timing to generate a rotating magnetic field. This rotating magnetic field causes the rotor 4 to rotate in the direction of arrow A in FIG.

The FG magnet 2'is fixed to the outermost peripheral portion of the drive magnet yoke 3 fixed to the rotor yoke 4 and is magnetized for 120 poles in total. On the surface portion of the iron substrate 7 facing the FG magnet 2 ', 120 power generating line elements 7a having a pattern as shown in FIG. 12 are formed by etching a copper pattern or the like.

With the above structure, when the rotor yoke 4 is started to rotate, a sine wave having a frequency corresponding to the rotation speed of the rotor yoke 4 is generated from the power generating line element, and a constant speed rotation control is performed by a control circuit (not shown). Be done. When the rotor yoke 4 rotates, the position detecting magnet 13 fixed to the rotor yoke 4 also rotates, so that the position detecting magnet 13 is rotated by the position detecting Hall element 14.
By detecting the change in the magnetic field due to, the position detection signal which is one pulse signal is generated for one rotation of the rotor yoke 4. With this pulse signal, the rotational position of the rotating body and the like can be detected. The position detection signal output by the position detection Hall element 14 has a waveform as shown in FIG. This position detection signal is shown in FIG.
When input to the comparator 15 shown in FIG.
A position detection signal as shown in (b) is obtained.

However, the above-described conventional rotational position detecting method has the following problems.

(1) The rotational position detecting magnet 13 is
Since it is attached to the outermost peripheral surface of the rotor yoke and the magnetic circuit formed by this magnet is open, magnetic flux leaks as leakage magnetic flux. For this reason, when this motor is used for rotating the disk of the magnetic recording / reproducing apparatus, the leakage magnetic flux enters the magnetic head for magnetic recording / reproducing, which may interfere with accurate recording / reproducing of information.

(2) A space for providing the Hall element 14 and the magnet 13 for detecting the rotational position is required, which hinders downsizing and thinning of the multi-phase brushless motor, and further increases the product cost. is there.

The invention of Japanese Patent Application No. 4-3187 previously filed by the applicant of the present invention has solved these problems, and various problems due to magnetic flux leakage do not occur. , A low-cost, compact / thin electromagnetic rotating machine with a reduced number of components is proposed. According to the above invention, the rotational position of the motor can be detected by using the FG signal generating means for detecting the speed signal, which generates the AM-modulated signal of one cycle per one rotation. Since the use magnet and the rotational position detecting element can be omitted, the electromagnetic rotating machine itself can be made smaller and thinner, and the leakage magnetic flux can be prevented.

The above invention will be described below with reference to the drawings. The above invention discloses a spindle motor having a rotation position detecting device, which is applied to a circumferentially opposed spindle motor. FIG. 5 shows a pattern of the power generation line element 7b. The power generation line element 7b is formed by etching a copper pattern or the like on a substrate 7 made of iron or the like. There is no power generation line element pattern in the range of the angle θ ₀ , but this is due to the coil 10 and Hall elements 12a, 12b,
This is for arranging a pattern for connecting 2c and a terminal of an integrated circuit for driving and controlling the electromagnetic rotating machine.

The rotation speed signal, which is the output from the entire power generating line element 7b, is input to the amplifier 16a to generate the main FG signal, and the power generating line element from a part of the power generating line element 7b over an angle θ ₁ range. The rotation speed signal is input to the amplifier 16b to generate a sub FG signal. Therefore, this is different from the configuration shown in FIGS. 11 and 12 in which the rotation speed signal from the entire power generating line element 7a is input to only one amplifier 16a. The main FG signal from the amplifier 16a is input to the rotation position detection circuit 100 and the rotation speed control circuit 200. Sub FG from amplifier 16b
The signal is input to the rotational position detection circuit 100.

FIG. 6 is a plan view showing a magnetization pattern of the FG magnet in the rotor unit 40. The rotor unit 40 of the present embodiment is a modification of the conventional rotor unit shown in FIGS. 10 and 11, and is the rotor unit shown in FIGS. 10 and 11 except for the parts having different reference numerals. The parts which are substantially the same as the parts of are used.

The position detecting magnet 13 (FIG. 11), the Hall element 14 and the like are also unnecessary. For this reason, the motor is considerably miniaturized. Further, as can be seen from FIG. 6, the magnetization pattern of the FG magnet 2 is such that the FG magnet 2 ′ of the conventional example is magnetized at the same pitch as the power generating wire element pattern over the entire circumference (FIG. 10). On the other hand, the non-magnetized portion is formed over the angle α. The angle α of the non-magnetized portion and the angle θ ₁ of the power generating line element portion that contributes to the sub-FG signal shown in FIG. 5 have the relationship of the following equation (1) (for example, the magnetization pattern and the pitch of the power generating line element). Is 3 °, α is preferably θ ₁ + (3 ° to 6 °)).

Α> θ ₁ (1) In other words, the number of pulses generated in the rotation speed signal is the rotor 1
The number of poles M, in which the FG magnet 2 faces the entire surface of the power generating line element when the number of rotations is P / 2, is represented by the formula (2).

M <P (where P is the total number of poles) (2) The number N1 of power generating line elements contributing to the main FG signal is expressed by the equation (3).

N1 ≦ M <P (3) The number N2 of power generating line elements contributing to the sub-FG signal is expressed by the equation (4).
Indicated by.

N2 <(P−M) (4) From the above, the number N1 of power generating line elements contributing to the main FG signal is the number of poles of the facing FG magnet for one rotation of the rotor. Although there is an increase or decrease, the main FG signal is always output because there are magnets facing each other,
Moreover, as shown in FIG. 5, only when the pattern of the power generation line element 7b does not exist at the angle θ ₀ , the signal waveform (FIG. 7A) that is AM-modulated once per rotation is obtained, and the rotor rotation speed is detected. Used as a signal. On the other hand, the number N2 of power generation line elements contributing to the sub FG signal is such that the output of the sub FG signal becomes zero only once per rotation because the opposing FG magnet may disappear for one rotation of the rotor. It becomes a waveform (Fig. 7c). If the rotational position where this output becomes zero is detected, the rotational position detection signal will be obtained. What is important is that the spread angle θ ₁ of the number N2 of power generating line elements contributing to the sub-FG signal is slightly smaller than the angle α of the facing non-magnetized portion, and the timing at which the power generating line element N2 does not generate power is roughly the main. That is, it is only one shot of the pulse of the FG signal.

That is, the sub-FG signal is the rotor unit 40.
Is AM-modulated in one cycle during one rotation, the minimum value of the amplitude of the AM-modulated component is detected, and immediately after that, at the rising or falling timing of the pulse generated by differentiating the main FG signal. The rotation position detection signal (index signal) is generated.

In FIGS. 5 and 6, the magnetic field generated by the FG magnet 2 changes as the rotor unit 40 rotates, and this change is detected by the power generating line element 7b. The output of the power generation line element 7b is the amplifier 16 shown in FIG.
It is amplified by a and 16b and sent to the rotational position detection circuit 100 as a main FG signal and a sub FG signal, respectively.

FIG. 7 is a timing chart of each signal in the rotational position detection circuit 100, and FIG. 8 is a rotational position detection circuit 1
It is a block diagram showing 00. The main FG signal shown in FIG. 7A is the output of the amplifier 16a. As can be seen from FIGS. 5 and 6, the output of the main FG signal is large and
The M modulation is suppressed as much as possible. This is because the main FG signal is used as the rotation speed signal and as the clock of the index signal. AM of main FG signal
The modulation component has a maximum output amplitude when the angle θ ₀ where there is no generator line element and the non-magnetized part α of the FG magnet 2 face each other, and when the magnetized part faces each other, the output amplitude is Take the minimum value. If the power generation line element patterns contributing to the main FG signal are arranged all around (θ ₀ =
0), AM modulation component disappears.

After the main FG signal is differentiated, it is binarized (by the differentiating circuit 101 and the comparator 102 in FIG. 8) and used as sample and hold circuits 104 and 106 and a rotational position detecting clock (FIG. 7B). Used. Further, the main FG signal is output from the comparator 1 as shown in FIG.
It is binarized by 03 and input to the rotation speed control circuit 200.

The rotation speed control circuit 200 compares the reference clock (1 MHz in FIG. 8) with the clock generated from the main FG signal to generate a speed control signal, and the coil 10 is driven through a drive circuit (not shown). The motor rotates at a constant speed by controlling the current flowing through the motor. Further, the rotation speed control circuit, when the rotation of the motor enters a certain range with respect to the set rotation speed (± 10 in FIG. 10).
%) Generates a rotation speed lock signal. How to use this signal will be described later.

The signal shown in FIG. 7C is a sub-FG signal, which is the output of the amplifier 16b. As described above, there is only one place where the output is almost zero during one rotation of the rotor unit 40. This was the most important point in the prior invention (Japanese Patent Application No. 4-3187). That is, the output level of the sub FG signal is determined by the FG magnet 2
FG due to variation in magnetizing strength and variation in assembly accuracy
It changes due to changes in the gap between the magnet 2 and the power generation line element 7b, changes in the magnetic flux density due to changes in temperature, and the like. Also,
The output also changes when the set rotational speed is different. When an index signal is generated by detecting the level of the AM modulation component of the FG signal as in the prior invention (Japanese Patent Application No. 4-3187), a detection method that is not affected by the above level change is required. Become. Therefore, detecting the timing when the amplitude of the sub-FG signal becomes almost zero is an effective means.

Next, a method of detecting the minimum value (timing at which the output becomes almost zero) of the sub-FG signal will be described.
The sub-FG signal is sent to the sample hold circuit 104 (FIG. 8).
Is input to the clock CLA and is sampled at the rising timing of the clock CLA (FIG. 7B). In FIG.
The pulse generator 105 generates a pulse having a narrow negative polarity whose falling edge is synchronized with the rising edge of the clock CLA, and outputs it as a sample hold signal to the sample hold circuit 104. The sample hold circuit 104 samples when the sample hold signal is low and holds it when it is high. The output signal SHA of the sample hold circuit 104 is shown in FIG.

The output signal SHA is the sample and hold circuit 1
06, and sampling is performed at the falling timing of the clock CLA. Pulse generator 107
Generates a narrow negative pulse whose falling edge is synchronized with the falling edge of the clock CLA and outputs it as a sample hold signal to the sample hold circuit 106. Similar to the sample hold circuit 104, the sample hold circuit 106 samples when the sample hold signal is low and holds it when it is high. The output signal SHB of the sample hold circuit 106 is shown in FIG.
Shown in.

Next, the output signals SHA and SHB are compared with each other by the comparator 1.
08 will be compared. At this time, the sample hold circuit 10
The comparators 108 and 106 when sampling is performed and when the voltage of the AM modulation component of the sub FG signal exceeds a certain voltage (a threshold value smaller than the maximum value of the sub FG signal).
Stops its operation. This is to prevent erroneous detection of the comparator 108, and particularly to prevent erroneous operation due to extra AM modulation components due to surface deflection of the FG magnet when the amplitude of the sub FG signal is large.

In FIG. 8, the output signal SHA is set to the sub-F.
The voltage of one third of the AM modulation component of the G signal (V _ref = V _CC
/ 2 + V _sub / 3) and the output signal (COMP2: FIG. 7 (f)) of the comparator 109 and the pulse generator 1
The NAND with the outputs of 05 and 107 is connected to the NAND circuit 110.
Therefore, the operation of the comparator 108 is prohibited by the output of the NAND circuit 110. Output signal COMP1 of the comparator 108
Is shown in FIG. In the figure, the shaded areas are the output signals SHA and S.
It indicates that the HB level is the same and the output is indefinite.

The output COMP1 of the comparator 108 is input to the data terminal of the D latch circuit 112. The output of the pulse generator 105 is delayed by the delay circuit 111 so as to match the input signal of the D latch circuit 112, and is input to the clock terminal C of the D latch circuit 112. Further, in order to prevent malfunction of the D latch circuit 112 at the time of starting and stopping the motor, the rotation speed control circuit 2
The rotation speed lock signal output from 00 causes the D latch circuit 112 to operate only when the rotation speed is within a certain range of the target rotation speed. In FIG. 8, the output range of the lock signal is set to be output within ± 10% of the reference value. The output Q of the D latch circuit 112 is shown in FIG. The rising timing of this signal is the rotational position detection timing. Since this rotational position detection signal is synchronized with the clock CLD (FIG. 7 (h)) which is the output of the delay circuit 111, the rotational position detection signal is not affected by the change in the timing due to the change in the offset voltage of the comparator or the like.

5 and 6, the rotor unit 40
Is rotating in the direction of arrow B, the rotational position detection signal (rotation of FIG. 7 (i)) occurs immediately after one of the power generation line elements 7b-1 and the boundary line 17-1 of the FG magnetization pattern face each other. The timing at which the signal rises in the position detection signal) occurs.

In the above description, the hold timing of the sample hold circuit 104 is the rising edge of the clock CLA, and the hold timing of the sample hold circuit 106 is the falling edge of the clock CLA.
The latch timing of the D latch circuit 112 is clock CL
At a certain moment between the rising edge and the falling edge of A, the hold timing of the sample hold circuit 104 is the falling edge of the clock CLA, and the hold timing of the sample hold circuit 106 is the clock CLA.
Is the rise of. Further, the latch timing of the D latch circuit 112 may be a certain moment between the falling edge and the rising edge of the clock.

As shown in FIG. 6, when a non-magnetized portion is set in a part (angle α) on the circumference of the FG magnet 2, the attraction force between the FG magnet 2 and the substrate 7 (made of iron) is increased. There is a possibility that unbalance will occur and the rotation accuracy of the motor will be deteriorated. In addition, there is a possibility that the bearing and the like may be deteriorated.

In FIG. 9, the magnetized portion is formed so as to eliminate the above-mentioned imbalance of the attraction force. Magnetization is performed in the range of the angle α at twice the pitch of the power generation line elements. With this structure, the portion magnetized at the double pitch generates the attractive force, but does not contribute to the output of the power generating line element.
There is no imbalance in the attraction force, and there is no worry of deteriorating the rotation accuracy, and there is no worry of bearing deterioration.

[0037]

However, when the magnetization shown in FIG. 9 is carried out in order to eliminate the imbalance of the attraction force, the sub-FG signal becomes the FG signal as shown in the signal (c ') of FIG. AM-modulated at half the frequency, and position detection signal (FIG. 8: D latch circuit 112Q output, FIG. 2:
Q1 output) may malfunction.

Therefore, in view of the above-mentioned problems, the present invention, even when the sub-FG signal includes a high-order AM modulation component,
An object of the present invention is to provide a circuit capable of preventing a malfunction of the rotation position detection circuit.

[0039]

A rotational position detecting circuit of the present invention comprises a rotating speed detecting magnet arranged on a rotor of an electric motor having a rotor and a stator in a multi-pole magnetized manner, and a comb-like tooth on the stator. It comprises a rotational speed detection mechanism consisting of a power generating line element bent and arranged in a, there is a region on the rotor that contributes to power generation in part, from the power generating line element,
Based on the first and second rotation speed signals, the first rotation speed signal and the second rotation speed signal that undergoes AM modulation whose level is close to zero for one rotation of the rotor are obtained. A rotation position detection circuit for an electromagnetic rotating machine that generates a rotation position signal by adding a high-order AM modulation component near the level where the AM modulation component of the second rotation speed signal is close to zero. In this case, a malfunction prevention circuit for preventing malfunction due to the high-order AM modulation component is provided.

Preferably, the malfunction prevention circuit samples and holds the second rotation speed signal at the leading edge of the first pulse formed through the first comparator after differentiating the first rotation speed signal. No. 1 sample-hold circuit, a second sample-hold circuit that samples and holds the output of the first sample-hold circuit at the falling edge of the first pulse, an output of the first sample-hold circuit, and a second sample A second comparator for comparing the output of the hold circuit, a first latch circuit for latching the output of the second comparator in synchronization with the first latch clock, and
The first latch clock is synchronized with the timing when the hold outputs of the first and second sump-hold circuits output in synchronization with the timing from the rising edge to the falling edge of the pulse of A first clock generation circuit to be supplied to the first latch circuit; a second latch circuit that latches the output of the first latch circuit at the falling edge of the first clock; and an output of the first latch circuit An OR circuit that ORs the output of the second latch circuit,
The output of the logical sum circuit is latched in synchronization with the second latch clock and is output as a normal rotational position detection signal, and the third latch circuit and the first and second latch circuits provided to the logical sum circuit. A second clock generation circuit that supplies the second latch clock to the third latch circuit at the timing when the output reaches the third latch circuit via the logical sum circuit.

Further, at the timing when the first and second sample and hold circuits are sampling and at the timing when the amplitude of the second rotation speed signal is a certain value or more with respect to its maximum value, The operation of the second comparator is prohibited, and the first and third latch circuits are enabled only when the rotation speed of the electromagnetic rotating machine is within a certain range with respect to the target rotation speed. Is preferred.

[0042]

According to the present invention, in the rotational position detection circuit for detecting the rotational position of the motor by utilizing the power generation means for detecting the speed signal which generates the AM-modulated signal of one cycle per one rotation, When a high-order AM modulation component is added to the signal, for example, it is magnetized in a range of an angle α that does not contribute to power generation at twice the pitch of the power generation line element, and AM of a frequency half the FG frequency is used. Even when the modulation component is included in the speed detection signal, the rotational position can be detected without malfunction, so that the imbalance of the attraction force is eliminated, the rotation accuracy is not deteriorated, and the bearing is not deteriorated. Disappear.

[0043]

Embodiments of the present invention will now be described with reference to the drawings. 1 is a block diagram showing an embodiment of a rotational position detection circuit for an electromagnetic rotating machine of the present invention, FIG. 2 is a timing chart showing the operation of each part of the embodiment of FIG. 1, and FIG.
It is a figure which shows the structure of the circumferentially opposed spindle motor in which the Example of FIG. Further, FIG. 1 mainly shows only a circuit portion for preventing a malfunction due to a high-order AM modulation component in the rotational position detection circuit, and omits other portions since they are the same as the conventional one in FIG. There is. As is apparent from FIG. 3, in this embodiment, the position detecting magnet 13 and the Hall element 14 are unnecessary.

The output of the D latch circuit 112 (shown in FIG. 8) is input to the D latch circuit 114 which is latched by the clock CLC (FIG. 7: 107 pulse generator output). Outputs Q1 of the D latch circuits 112 and 114
Q2 is input to the OR circuit 115 and output (Q1 + Q
2) is output. The D latch circuit 117 receives the output (Q1
+ Q2) to clock CLE (clock CLD (FIG. 7:
The output of the delay circuit 111) is latched by the clock obtained through the delay circuit 116).

The rising timing of the output Q3 of the latch circuit 117 is used as the rotational position detection signal.
The rotational position detection signal Q3 is used as a trigger for the time constant circuit 118, and is output from the time constant circuit 118 as an index signal ID after a certain delay time.

The threshold level of the time constant circuit 118 is determined by the reference voltage circuit 119, and the delay time is set to an appropriate value by changing the threshold level according to the rotation speed of the motor. It is possible. The ability to change in this way is necessary for ensuring proper operation in a floppy disk drive or the like.

Next, the operation of the rotational position detection circuit of the embodiment shown in FIG. 1 will be described with reference to FIG. C'is F
The output waveform of the sub FG signal containing the AM modulation component of the frequency of 1/2 of the G frequency is shown (output of the amplifier 16b in FIG. 5). Since the peak value of the signal waveform changes alternately, the output Q1 of the D latch 112 changes as shown in FIG. In the prior invention (Japanese Patent Application No. 4-3187), since the rising timing of the output Q1 is the rotational position detection signal, it can be understood that malfunction occurs.

The output Q1 of FIG. 2 is input to the data terminal of the D latch circuit 114 and latched at the timing of the clock CLC (FIG. 7: 107 pulse generator output). Only the timing of about half the clock cycle with respect to the output Q1. The shifted output Q2 of FIG. 2 is output.

The outputs Q1 and Q2 of FIG.
Are added and output as an output (Q1 + Q2). The output from the OR circuit 115 is the D latch circuit 11
The data is input to the data terminal 7 and is latched by the clock CLE which is the clock CLD that has passed through the delay circuit 116, and the output of the logic level high (Q1 + Q2) is detected after φ _{0 is} detected in the same manner as the invention of the previous application (see FIG. 7). The output Q3 of FIG. 2 in which the timing of the first detected clock CLE is the rising timing of the rotational position detection signal is obtained. The rising timing is the invention of the prior application (Japanese Patent Application No. 4-3187).
Signal), the delay amount of the delay circuit 114 (Δ
The output is delayed by (θ) (θ ₀ + 3 ° + Δθ). In summary, the position detection signal is output only when the peak value of the sub FG signal becomes small for two consecutive clocks. That is, the influence of the high-order AM modulation component is removed, and the rotational position detection circuit operates normally.

FIG. 4 shows an example of a circuit configuration using concrete parts. A D latch circuit 4013, an OR circuit 4071, a delay circuit 74LS04 and a differentiating circuit are used.

The invention of the prior application (Japanese Patent Application No. 4-3187)
As described above, when the sub FG signal of the comparator 108 is large, the malfunction prevention circuit due to the extra AM modulation component due to the surface deflection of the FG magnet and the D latch circuits 112 and 117 are stopped at the time of starting the motor. A malfunction prevention circuit is added.

[0052]

As described above, in the electromagnetic rotating machine according to the present invention, the magnetic field strength formed between the two electromagnetic coupling elements for detecting the rotation speed is AM-modulated with 1 ppr, and the high-order AM modulation is performed. Even when the component is included in the rotational position detection signal, the rotational position signal can be generated from the AM modulation component. For this reason, the rotation speed detection magnetic field generating means is magnetized in a range of an angle α that does not contribute to power generation at twice the pitch of the power generating line elements, and A of a frequency half the FG frequency is used.
Even if the M modulation component is included in the speed detection signal, the rotational position can be detected without malfunction, so that the imbalance of the attraction force is eliminated, and the rotation accuracy is not deteriorated and the bearing is not deteriorated. There is an effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a rotational position detection circuit of the present invention.

FIG. 2 is a timing chart showing the operation of the embodiment shown in FIG.

FIG. 3 is a sectional view showing the structure of a motor in which the embodiment of FIG. 1 is used.

FIG. 4 is a block diagram showing an example in which the rotational position detection circuit of the embodiment of the present invention is realized by using concrete parts.

FIG. 5 is a prior art invention of prior art (Japanese Patent Application No. 4-3187).
No.) example of the power generation line element.

FIG. 6 is a diagram illustrating a magnetization pattern of an FG magnet (velocity detecting magnet) in the example of the related art.

FIG. 7 is a timing chart for explaining the operation of the embodiment of the related art.

FIG. 8 is a block diagram showing an example of a conventional technique.

FIG. 9 is a diagram for explaining a magnetization pattern of an FG magnet in another example of the related art (also used in the example of the present invention).

FIG. 10 is a plan view illustrating the structure of a three-phase brushless motor to which a conventional technique is applied.

11 is a partial cross-sectional view of the motor shown in FIG.

12 is a diagram showing a line element pattern for FG signal detection of the motor of FIG.

FIG. 13 is a waveform diagram showing a relationship between a position detection element output and a position detection signal in the conventional technique.

FIG. 14 is a diagram showing input / output of a comparator in the related art.

[Explanation of symbols]

 1 Drive Magnet 2 FG Magnet (Magnet for Speed Detection) 4 Rotor Yoke 7a, 7b Generator Line Element Section 112, 114, 117 D Latch Circuit 115 OR Gate Circuit 116 Delay Circuit 118 Time Constant Circuit

Claims (4)

[Claims] 1. A rotation comprising a rotation speed detecting magnet arranged on a rotor of a motor having a rotor and a stator in a multi-pole magnetized manner, and a power generating line element arranged on the stator in a comb-like shape. A speed detection mechanism is provided, and there is a region on the rotor that partially contributes to power generation. From the power generation line element, a first rotation speed signal and one rotation per rotation of the rotor are provided.
A rotation position of an electromagnetic rotating machine, which is provided so as to take out a second rotation speed signal subjected to AM modulation having a level close to zero degree, and generates a rotation position signal based on the first and second rotation speed signals. In the detection circuit, when a high-order AM modulation component is added near the level where the AM modulation component of the second rotation speed signal is close to zero, malfunction caused by the high-order AM modulation component may occur. A rotation position detection circuit having a malfunction prevention circuit for preventing the rotation position detection circuit. 2. The malfunction prevention circuit detects a change in the amplitude of the AM modulation component once per rotation of the second rotation speed signal, detects a minimum value of the amplitude, and follows the detection of the minimum value. Occurs at the rising or falling timing of the pulse formed through the first comparator after differentiating the first rotation speed signal, one rotation position signal is generated for each rotation of the rotor. A first sample-hold circuit that samples and holds the second rotation speed signal at the rising edge of the first pulse formed through the first comparator after differentiating the rotation speed signal, and the falling edge of the first pulse Compares the output of the first sample and hold circuit with the output of the first sample and hold circuit and the output of the second sample and hold circuit. A second comparator that latches the output of the second comparator in synchronization with the first latch clock, and a first latch circuit that latches the output of the second comparator in synchronization with the timing from the rising edge to the falling edge of the first pulse. First clock generation for supplying the first latch circuit with the first latch clock at the timing when the hold outputs of the first and second sump-hold circuits output by the first latch circuit reach the first latch circuit. Circuit, a second latch circuit that latches the output of the first latch circuit at the falling edge of the first clock, and the logical sum of the output of the first latch circuit and the output of the second latch circuit An OR circuit, a third latch circuit for latching the output of the OR circuit in synchronization with the second latch clock, and outputting it as a normal rotational position detection signal, and a first and a first circuit applied to the OR circuit. 2 latch circuits A second clock generation circuit for supplying a second latch clock to the third latch circuit at the timing when the output reaches the third latch circuit via the logical sum circuit. The rotational position detection circuit according to claim 1. 3. At the timing at which the first and second sample and hold circuits are sampling and at the timing at which the amplitude of the second rotation speed signal is a certain value or more with respect to its maximum value, The rotational position detecting circuit according to claim 2, wherein the operation of the second comparator is prohibited. 4. The rotation according to claim 2, wherein the first and third latch circuits are enabled only when the rotation speed of the electromagnetic rotating machine is within a certain range with respect to the target rotation speed. Position detection circuit.