JPH052803Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention will be explained in the following order.

A. Field of industrial application B. Outline of the invention C. Conventional technology D. Problem that the invention aims to solve E. Means for solving the problem (Fig. 1) F. Effect G. Example G1. Configuration (Fig. 1) G2 Signal selection during forward rotation (Fig. 2, 3)
(Fig.) G3 Malfunction prevention (Fig. 4) G4 Signal selection during reverse direction rotation (Fig. 5)
For example, it can be applied to detecting the rotational position of a capstan motor in a video tape recorder (VTR).

B. Summary of the invention The present invention provides a rotational position detection device for a rotating device that detects and counts the zero-crossing points of a multiphase sine wave signal based on the rotation of the rotating device to detect the rotational position of the rotating device. By selecting multi-phase sine wave signals in a predetermined order according to the rotation direction and obtaining a zero-cross point detection output according to the rotation direction, malfunctions can be prevented and accurate and detailed rotation positions can be detected. At the same time, the direction of rotation can also be detected.

C. PRIOR TECHNOLOGY In a VTR, it is necessary to accurately and minutely detect the position of the magnetic tape in order to accurately stop the magnetic tape at a desired position or to travel a predetermined distance with accuracy. .

For this reason, time code signals (TC) and control signals (CTL) were recorded along the length of the magnetic tape, and these signals were played back to detect the tape position. Therefore, according to this method, the tape position can only be detected with an accuracy of one frame or one CTL.

By the way, there is an arbitrary speed recording VTR that can record video signals on tape at an arbitrary speed in order to record animation images and the like. This arbitrary speed recording VTR
With the tape running at low speed or standing still, one frame of video signals is recorded so as to form a slanted track (having the same inclination as normal recording) that meets the standard, and then the tape is run in the longitudinal direction. A tape that is used for so-called time-lapse recording, in which the video signal for one frame is recorded in the same way after traveling for one track, that is, one CTL interval, and on which CTL or TC is recorded in advance. is used.

In this type of VTR, for example, when the tape is stopped and one frame worth of video signal is recorded, the capstan motor that feeds the tape plays back the time-lapse video in normal playback mode.
Since it is not possible to use a stepping motor that stops intermittently, a DC motor is used.
Therefore, even if you try to run the tape for one frame based on the CTL or TC recorded on the tape in advance, it will not be possible to stop it accurately.
This causes a stopping error of about 1/10. If time-lapse recording is performed without correcting this error, the intervals between adjacent tracks will not be constant and the reproduced video signal will contain a lot of noise. The same applies when recording is performed by running the tape at a low speed.

In order to cope with this interval, it is necessary to control the running of the tape by detecting the rotational position of the capstan motor with a precision of several tenths to several hundredths of one CTL interval.

Therefore, in order to precisely detect the rotational position of a capstan motor in detail and perform time-lapse recording, a rotational position detection device having the configuration shown in FIG. 6 has been proposed.

In FIG. 6, a rotating body 11 of a rotational position detecting device 10 is connected to the shaft of a DC motor 2 that drives a capstan 1. As shown in FIG.

The circumference of the rotating body 11 is equally divided into about several tens of sections, and each section is alternately magnetized with north or south poles as shown in the figure. Two magnetoelectric transducers 12a and 12b, such as Hall elements, are disposed facing the periphery of the rotating body 11 as a sine wave signal extraction device, and convert magnetic flux changes that change due to the rotation of the rotating body 11 into voltages. is being converted to .
The outputs of both converters 12a and 12b are supplied to the zero-crossing point detection circuit 14 as equal amplitude voltage signals v _a and v _b via amplifiers 13 a and 13 b, respectively. The rotating body 11 is magnetized so that the voltage signals v _a and v _b have a sinusoidal waveform as shown in FIG. When the capstan motor 2 rotates in the direction of arrow 3 and the tape runs in the forward direction, the phase of the output signal _v
It is provided at a position delayed by 90 degrees from the phase of the output signal v _a of a.

The zero-cross point detection circuit 14 detects the zero-cross points of the voltage signals v _a and v _b and provides a pulse signal S _p to the counter 15 . The counter 15 receives the reproduced CTL supplied from the CTL reproduction magnetic head (not shown) to the input terminal 16 as a reset signal, counts up every time the pulse signal S _p is applied from the zero-crossing point detection circuit 14, and increases the count. The value is sent as a rotational position signal S _p of the rotational position detection device 10.

In the apparatus shown in FIG. 6, when the tape is run for the next time-lapse recording, sine wave signals v _a and v _b are applied from the magnetoelectric transducers 12 a and 12 b to the zero cross point detection circuit 14, and the zero cross point is detected. When the pulse signal S _p is applied to the counter 15, it is counted up.

Based on the count contents of the counter 15, for example, drive control is performed such that the rotational speed of the capstan motor 2 is gradually decreased so as to stop the capstan 1, that is, the tape at a predetermined position, or , detects an error in the stop position of the capstan 1, and performs a correction operation to correct the error.

However, in the conventional device shown in FIG.
The number of magnetized sections on the periphery of the rotating body 11 depends on the mechanical structure,
Due to manufacturing problems with the magnetizing means, etc., the number of sections is limited to, for example, about 100 sections, and the detection accuracy of the rotational position of the capstan motor 2 (position of the tape) is also limited. Therefore, this detection accuracy may not be sufficient for severe problems such as making the intervals between tracks formed in time-lapse recording constant.

A first method for improving the detection accuracy of the rotational position is to detect the phase based on the output level of the sine wave signal v _a (or v _b ) of the magnetoelectric transducer 12a or 12b. However, in this method, the amount of level change relative to the phase is small near the peak value of the sine wave signal, resulting in poor accuracy.

A second method is to detect the rotational position by detecting the phase based on the differential coefficient of the sine wave signal v _a (or v _b ). However, with this method, the variation in the differential coefficient near the zero-crossing point of the sine wave signal is small, resulting in poor accuracy.

Thirdly, there is a method of increasing the frequency of zero-cross point detection by providing a large number of magneto-electric transducers and varying the phase of the sine wave signals from them, as shown in FIG. 8, to improve accuracy. However, according to this method, it is difficult to maintain the phase between the magnetoelectric transducers with high accuracy, and as the number increases, the device becomes complicated and expensive.

In order to solve the problems of the conventional device as described above, the present applicant synthesizes a multiphase sine wave signal from two-phase sine wave signals v _a and v _b using an electronic circuit, and synthesizes this multiphase sine wave signal. We have already proposed a rotational position detection device for rotating equipment that improves detection accuracy by detecting zero-crossing points of wave signals (see Utility Model Application No. 146050/1983).

Hereinafter, with reference to FIGS. 8 and 9, a previously proposed rotational position detection device for rotating equipment will be described.

FIG. 9 shows the configuration of the previously proposed device. In FIG. 9, parts corresponding to those in FIG. 6 are given the same reference numerals, and redundant explanation will be omitted.

In FIG. 9, 20 is a sine wave signal synthesis circuit, which is composed of an addition circuit 21 and a subtraction circuit 22. The adder circuit 21 and the subtracter circuit 22 each include operational amplifiers OP ₁ and OP ₂ , to which the output signals v _a and v _b of both amplifiers 13a and 13b are supplied. The phase of the output signal v _b of the amplifier 13b is delayed by 90° from the output signal v _a of the amplifier 13a, and the amplitudes of both signals v _a and v _b are equal, so the phase of the output signal v c of the adder circuit 21 is delayed by 90° from the output signal v _a of the amplifier 13 a. The output signal of the subtraction circuit 22 is delayed by 45° from the output signal v _a.
The phase of v _d is 45° from the output signal v _b of amplifier 13b.
I'll be late. The amplitudes of the output signals v _c and v _d of the addition circuit 21 and the subtraction circuit 22 are determined by the resistors R ₁ to R ₄ and R ₅ to _{R 8}
By appropriately selecting the value of , both amplifiers 13a and 13
b is made equal to the amplitude of the output signals v _a and v _b .

Reference numeral 24 denotes a zero-cross point detection circuit, which is composed of, for example, four sets of window comparators and an exclusive OR circuit (hereinafter abbreviated as EX-OR circuit). The output signals v _a , v _b , v _c and v _d of both the amplifiers 13 a and 13 b, the adder circuit 21 and the subtracter circuit 22 are supplied to the zero cross point detection circuit 24, and as shown in FIG. Phase sine wave signal v _a ~
All zero crossing points of v _d are detected and the detection pulse signal S _p is supplied to the counter 15 . The rest of the configuration is the same as the conventional device shown in FIG.

In the configuration shown in FIG. 9, when the tape is run and the rotating body 11 rotates, the zero cross point detection circuit 2
4 are given four-phase sine wave signals v _a to v _d . At this time, the detection frequency of the zero-crossing point in the zero-crossing point detection circuit 24 is as shown in FIG.
It is twice as large as that shown in Figure). Therefore, the number of zero-crossing points is doubled, the contents of the counter 15 have twice as much information as before, and the rotational position of the capstan motor 2, that is, the tape position, can be determined with a simple configuration compared to the conventional device. This enables highly accurate and detailed detection. In this way, it is possible to control the time-lapse recording so that the same recording track as in normal recording can be obtained.

D. Problems to be Solved by the Invention However, in the already proposed device shown in FIG.
When pulse noise N _b is mixed near the zero-crossing point of the output signal v _b of b, as shown in Fig. 10A,
The waveform of the signal v _b is disturbed, and pseudo zero-crossing points occur in addition to regular zero-crossing points. Therefore, the output of the window comparator (not shown) of the zero crossing point detection circuit 24 has the following
A narrow pulse Pn ₁ appears at a position corresponding to the pulsed noise N _b .

Furthermore, if pulse noise N _a is mixed in a position away from the zero-crossing point of the output signal v _a of the amplifier 13a, depending on the position of the mixed noise, for example, the output of the adder circuit 21 may be affected as shown in FIG. The waveform near the zero-crossing point of the signal v _c may be disturbed, and pseudo zero-crossing points may occur in addition to the regular zero-crossing points of the signal v _c . In this case as well, a narrow pulse Pn ₂ appears in the output of the window comparator of the zero-crossing point detection circuit 24 at a position corresponding to the pulse noise N _a , as shown in FIG.

The output pulse train of the window comparator is EX
-OR circuits (not shown) detect the rising and falling points of individual pulses, that is, the zero crossing points, but as mentioned above, the mixed noises N _b and N _a cause the sine wave signal v _b The waveforms of and v _c are disturbed,
When narrow pulses Pn ₁ and Pn ₂ caused by mixed noise appear in the output of the window comparator,
The zero crossing point detection output is as shown in C in the same figure.
A pair of pulses Pe ₁ and Pe ₂ appear corresponding to each rise and fall of pulses Pn ₁ and Pn ₂ , respectively.

As mentioned above, these two pairs of pulses Pe ₁ and Pe ₂
are caused by mixed noise and are supplied to the counter 15 together with the zero-crossing point detection outputs of the regular sine wave signals v _a to v _d . Therefore, there is a problem that an error occurs in the count contents of the counter 15, and the capstan motor 2, which is controlled based on the count contents, cannot accurately stop at a predetermined position.

Further, according to the previously proposed device, although the accuracy of detecting the position of the rotating body is improved, the rotation direction cannot be detected, and therefore, there is a problem in that a rotation direction detection means must be provided separately.

In view of this, an object of the present invention is to provide a rotational position detection device for a rotating body that is free from malfunctions due to noise, can stably detect a position with high precision, and can also quickly detect the direction of rotation. It is in a place where we provide.

E Means for Solving Problems The present invention provides first and second sine wave signals having a phase difference of 90 degrees that change according to rotation from a rotating body 11 connected to a rotating shaft of a rotating device 2. First and second sine wave signal extraction devices 12a, 12
b, and at least one first and second sinusoidal signal.
adding and subtracting a zero-crossing point between each zero-crossing point of the first and second sine wave signals, having a zero-crossing point having a predetermined phase interval with respect to each zero-crossing point;
A sine wave signal synthesis circuit 2 that forms a plurality of synthesized sine wave signals whose periods are equal to the first and second sine wave signals.
0, and when the rotating device 2 rotates in the forward direction, the selection control signal sequentially outputs the first and second sine wave signals and a plurality of composite sine wave signals with a predetermined phase interval. a first signal selection means 31 that selects signals in a first order in which they are arranged; and a rotating device 2.
rotates in the opposite direction, the selection control signal selects the first and second sine wave signals and the plurality of composite sine wave signals in a second order opposite to the first order. a signal selection means 41; first and second zero-cross point detection circuits 32, 42 for detecting zero-cross points of the outputs of the first and second signal selection means 31, 41, respectively; The first and second gate circuits 36 and 46 gate the outputs of the zero crossing point detection circuits 32 and 42 using gate signals, respectively, and the output signals of the first and second gate circuits 36 and 46 are counted. A counter 51 outputs a rotational position signal of the rotating device 2; a delay means 55 outputs a selection control signal at a predetermined timing based on the output value of the counter 51; a gate signal generation circuit 54 that outputs a gate signal that closes the first and second gate circuits 36 and 46;
and a rotation direction detection circuit 52 that detects the rotation direction of the rotating device 2 based on the outputs of the second gate circuits 36 and 46.

F Effect According to the present invention, the first or second signal selection means 31 or 41 selects a polyphase sine wave signal depending on the forward or reverse rotation direction of the rotating device 2.
v _a , v _b , v _c and v _d are selected in a predetermined order, and a zero cross point detection output is obtained from the first or second zero cross point detection circuit 32 or 42 in a predetermined order according to the rotation direction. Therefore, malfunctions are prevented, and the flip-flop is set or reset by this zero-cross point detection output, and the rotation direction is displayed.

G. Embodiment Hereinafter, an embodiment in which the present invention is applied to detecting the rotational position of a capstan motor in a VTR will be described with reference to FIGS. 1 to 5.

G1 Configuration The configuration of an embodiment of the present invention is shown in Fig. 1. In FIG. 1, parts corresponding to FIGS. 6 and 9 are designated by the same reference numerals, and redundant explanation will be omitted.

In FIG. 1, 31 is an electronic rotary switch, and its four fixed contacts 31 ₁ , 31 ₂ , 3
1 ₃ and 31 ₄ receive four-phase sine wave signals v _a ,
v _b , v _c and v _d are respectively supplied, and the movable contact 31
₀ is connected to one input terminal of each of a pair of comparators 33 and 34 of the zero-cross point detection circuit 32. Note that the sine wave signal synthesis circuit 20 is
The configuration is the same as that shown in the figure, and the levels of the output sine wave signals v _c and v _d are made equal to the levels of the sine wave signals v _a and v _b . The other input terminals of the comparators 33 and 34 are supplied with negative and positive reference voltages V _RB and V _RT , respectively, forming window comparators. Note that each reference voltage is set so that the zero level is approximately at the center of the window.
As a result, the approximate center of the output pulse of the zero-crossing point detection circuit coincides with the zero-crossing timing. The outputs of comparators 33 and 34 are EX-
The output of the EX-OR circuit 35 is supplied to one input terminal of a NAND gate 36.

41 is an electronic rotary switch, and 42 is a zero-crossing point detection circuit, which have the same configuration as the above-mentioned switch 31 and detection circuit 32, respectively. 4, and detailed explanation of the configuration will be omitted.

51 is an up-down counter, 52 is an RS flip-flop, and NAND gates 3 are connected to the up-side and down-side clock terminals of the counter 51.
6 and 46 outputs are provided, respectively, and
The set and reset terminals of flip-flop 52 are supplied with the outputs of NAND gates 36 and 46, respectively. Output of counter 51 (LSB)
is divided into two parts, one of which is directly supplied to one input terminal of the EX-OR circuit 53, and the other output is supplied to the EX-OR circuit 53 via an RC delay circuit.
is supplied to the other input terminal of The output of the EX-OR circuit 53 is output as a rotational position detection signal S _p and is also supplied to the monostable multivibrator 54 . The Q output pulse of the required width of this multivibrator 54 is commonly supplied to the other input terminals of both NAND gates 36 and 46.

Also, the LSB and 2SB of the output of the counter 51 are
The switching control signal S _s is supplied to both rotary switches 31 and 41 via the delay circuit 55 to control the connection position of each movable contact 31 ₀ and 41 ₀ . Further, the Q output of the flip-flop 52 is outputted as a rotation direction forward/reverse display signal Sd.

G2 Signal Selection During Forward Direction Operation In the above-described configuration, first, the selection of polyphase sine wave signals when the rotating body 11 rotates in the forward direction shown by arrow 3 will be described.

Initially, as shown in FIG. 1, the movable contact ₃₁₀ of one rotary switch 31 is connected to the first fixed contact 3
1 ₁ , and the movable contact 41 ₀ of the other rotary switch 41 is connected to the fourth fixed contact 41 ₄ . As will be described later, under this condition, both the LSB and 2SB of the output of the counter 51 are "0". Note that hereinafter, "0" represents a low logic level, and "1" represents a high logic level.

The operation is started at the timing shown by the one-dot chain line in FIG. 8, and among the four-phase sine wave signals,
A sine wave signal v _a is supplied to a zero cross point detection circuit 32 via a switch 31 . As shown in FIG. 2H, when the sine wave signal v _a rises from the negative region and crosses zero at time t _p1 , the zero-crossing point detection circuit 32 detects the width
Outputs the To detection pulse. This detection pulse is supplied to one input terminal of the NAND gate 36. At this time, since the output of the monostable multivibrator 54 supplied to the other input terminal is "1" as described later, the zero-cross point detection pulse of the detection circuit 32 is transmitted to the counter via the NAND gate 36. The counter 51 is supplied to the up side clock terminal of the counter 51 to increase the count value, and the LSB of the output of the counter 51 is raised from "0" to "1" as shown in FIG. This rise is EX−
The OR circuit 53 detects the leading edge detection pulse P _F as shown in FIG. The delay time Tm of this multivibrator 54 is set larger than the pulse width To of the zero-cross point detection pulse, and the Q output of the multivibrator 54 is
As shown in FIG. 5E, time Tm becomes "0" from the trailing edge of the zero-crossing detection pulse of the sine wave signal v _a . Therefore, during this period, NAND gate 36 is in a "closed" state and no noise pulses can reach counter 51 through NAND gate 36.

Furthermore, when time Tm has elapsed from the trailing edge of the zero-cross detection pulse, the monostable multivibrator 54
The output of Q becomes "1" as shown in E of the figure, so the NAND gate 36 is "open".
state, and a newly detected zero-crossing detection pulse is sent to the counter 51.

On the other hand, the delay time Ts of the delay circuit 55 for timing adjustment is set smaller than the delay time Tm of the monostable multivibrator 54, and the LSB of the switching control signal Ss from the counter 51 is as shown in FIG. , from the first zero crossing detection time t _p1
The signal is supplied to the rotary switch 31 after a delay of Ts. 2SB and LSB of the supplied switching control signal Ss
changes sequentially like 00, 01, 10 and 11, the movable contact 31 ₀ of the rotary switch 31 changes from the first to fourth fixed contacts 31 ₁ , 31 ₂ , 31 ₃ and 3
1 ₄ are connected in sequence. Therefore,
As shown in figure F, the LSB of the control signal Ss is “0”
At time t _s1 when the rotary switch 31 changes from 1 to 1, the movable contact 31 ₀ of the rotary switch 31 is switched from the first fixed contact 31 ₁ to the second fixed contact 31 ₂ , and the zero cross point detection circuit 32 wave signal v _c
is supplied.

As shown in FIG. 2H, at the first switching time _ts1 , the movable contact 31 of the rotary switch ₃₁
The voltage is from +ΔV _S of the sine wave signal v _a to the sine wave signal v _c
quickly descends to -V _S. At this time, as described above, since the NAND gate 36 is in the "closed" state, the noise accompanying the switching is blocked by the NAND gate 36, and there is no risk of causing the counter 51 to malfunction.

Next, when the sine wave signal v _c rises from the negative region and crosses zero at time t _p2 , the detection pulse from the detection circuit 32 passes through the NAND gate 36.
As shown in B and C of the same figure, the LSB of the output of the counter 51 is
falls to “0” again, and 2SB rises from “0” to “1”. Of these, the falling edge of LSB is EX
-OR circuit 53 detects the trailing edge detection pulse P _B as shown in FIG. This trailing edge detection pulse P _B is supplied to the monostable multivibrator 54, and the NAND gate 36 is kept in the "closed" state for a predetermined time Tm in the same manner as described above.

When time Ts has elapsed since the second zero-crossing detection time _tp2 , as shown in FIG. “Stand up. That is, the switching control signal
When Ss becomes "10", the movable contact ₃₁₀ of the rotary switch 31 is switched from the second fixed contact ₃₁₂ to the third fixed contact ₃₁₃ .

Similarly, as shown in FIGS. 3A and 3B, after the zero-crossing point of the sine wave signal v _b is detected at time t _p3 and the zero-crossing point of the sine wave signal v _d is detected at time t _p4 , The movable contact 31 ₀ of the rotary switch 31 is switched to the fixed contact 31 ₁ again. At this time, the sine wave signal v _d is rising from the negative region, while the sine wave signal v _a is falling from the positive region, and the voltage at the movable contact 31 ₀ when the rotary switch 31 is switched is , contrary to the previous three times, it rises quickly. Thereafter, after the four-phase sine wave signals v _a , v _c , v _b and v _d descend from the positive region and cross zero at times t _p5 , t _p6 , t _p7 and t _p8 , the rotary switch 31 The connection state shown in Figure 1 is restored.

During this time, the other rotary switch 41 is also being switched by the switching control signal _Ss , but when the 2-bit switching control signal changes sequentially to 00, 01, 10, and 11, the movable contact 41 of the switch ₄₁ is the first
As shown in the figure, the movable contact 3 of one switch 31
1 ₀ is delayed by one step, and the fourth, first, second and third fixed contacts 41 ₄ , 41 ₁ , 41 ₂ and 41 ₃
are sequentially switched and connected. The sine wave signal v _d supplied to the fourth fixed contact 41 ₄ and the one switch 31
a sine wave signal supplied to the first fixed contact 31 ₁ of
Since the phase is different from v _a , as is clear from Fig. 3, at the zero-crossing point t _p1 of the sine wave signal v _a , the sine wave signal v _d is falling in the negative region and does not cross zero. . Looking at the sine wave signals v _a , v _c and v _b supplied to the first to third fixed contacts 41 ₁ , 41 ₂ and 41 ₃ of the other switch 41 , it can be seen that the one switch 31 has advanced one step each. Each zero-cross point of the sine wave signals v _c , v _b and v _d supplied to the fixed contacts 31 ₂ , 31 ₃ and 31 ₄
At t _p2 , t _p3 and t _p4 , each is rising in the positive region and never crosses zero.

Therefore, when the rotating body 11 rotates in the forward direction,
4-phase sine wave signal via rotary switch 41
No detection pulse is output from the other zero-cross point detection circuit 42 to which v _a to v _d are supplied.

At this time, the set terminal of the RS flip-flop 52 and the up-side clock terminal of the counter 51 are also connected to one zero-crossing point detection circuit 3.
Since the first detection pulse of 2 is supplied, the Q output of the flip-flop 52 becomes "1" immediately after the start of forward rotation, and an appropriate display means quickly indicates that forward rotation is in progress. .

G3 Malfunction prevention Next, we will explain the case where pulse noise is mixed into the sine wave signal.

For example, if pulse noise is mixed in just before the zero-crossing point of the sine wave signal _vb , the waveform of the signal _vb will be disturbed, and a false zero-crossing will occur just before the normal zero-crossing point, as shown in Figure 4A. A dot is produced. During the forward operation as described above, the zero cross point due to this mixed noise is generated through the third fixed contact 31 ₃ and movable contact 31 ₀ of the rotary switch 31.
It is detected by the zero cross point detection circuit 32, and the detection pulse is supplied to the up side clock terminal of the counter 51. Then, as described above, the switching control signal _Ss is supplied from the counter 51 to the rotary switch 31, and the movable contact ₃₁₀ is switched from the third fixed contact ₃₁₃ to the fourth fixed contact ₃₁₄ . , even if a normal zero-crossing point of the sine wave signal v _b appears after this switching, the path to the detection circuit 32 is blocked, so the normal zero-crossing point will not be detected, and the output signal of the switch 31 will not be detected. The waveform becomes as shown in FIG. 4B. Therefore, in this case, the timing of the zero-cross point detection pulse is advanced by the mixed noise, as shown in FIG.

In addition, pulse noise may be caused by, for example, a sine wave signal v _a
If the mixture is far from the zero cross point of
As shown in , a zero-crossing point due to mixed noise may appear, for example, immediately after a normal zero-crossing point of the sine wave signal v _c . In this case, as shown in Figure B, the switching timing of the rotary switch 31 based on the detection of the normal zero-crossing point of the signal _vc is earlier than the zero-crossing point due to mixed noise.
As in the case described above, the path to the detection circuit 32 is blocked, and as shown in FIG.

As mentioned above, in this embodiment, the rotary switch selects four-phase sine wave signals in a predetermined order and supplies them to the zero-cross point detection circuit, so signals that are out of the predetermined order are blocked. Therefore, the total number of zero-cross point detection pulses does not change, and malfunction of the counter is prevented.

G4 Signal Selection When Rotating in Reverse Direction Next, the case where the rotating body 11 rotates in the opposite direction to the forward direction indicated by arrow 3 will be explained.

As mentioned above, when the rotating body 11 rotates in the forward direction, the sine wave signal v _b from the magnetoelectric transducer 12b is 90° smaller than the sine wave signal v _a from the magnetoelectric transducer 12a.
Since there is a delay, if the direction of rotation is reversed, the sine wave signal 12b will lead the sine wave signal 12a by 90 degrees. Then, the phase relationship between the two sinusoidal signals v _c and v _d synthesized from both is also reversed.

Again, the four-phase sine wave signal v _a shown in Figure 8 above
Looking at the phase relationship of ~v _d , v _a →v _c during forward rotation
The order of →v _b →v _d is v _d →v _b →v _c when rotating in the opposite direction.
It is clear that →v _a .

By the way, in the above explanation of the operation during forward rotation, the dash-dotted line in Figure 8 was the timing at which the operation started, but due to the periodicity of the sine wave signal, the timing was delayed by 360° from the phase of this dash-dotted point. The two-dot chain line of the phase may be the timing of starting the operation. With this two-dot chain line as the timing for starting the operation, the direction of the arrow F is the forward direction operation, and the direction of the arrow R is the reverse direction operation.

However, as is clear from FIG. 8, the four-phase sine wave signal during the forward direction operation and that during the reverse direction operation are symmetrical with respect to the two-dot chain line indicating the timing of the start of the operation. Therefore, in the above description of the forward direction operation, one rotary switch 3
1 and the zero-crossing point detection circuit 32 are replaced with the other rotary switch 41 and zero-crossing point detection circuit 42, respectively, and by replacing the sine wave signals v _a and v _d and v _c and v _b , respectively, when rotating in the reverse direction. Be able to explain the operation.

However, in the case of reverse rotation, the detection pulse from the zero-cross point detection circuit 42 is supplied to the down side clock terminal of the counter 51 and the reset terminal of the flip-flop 52 via the NAND gate 46. Therefore, the flip-flop 52 is reset and its Q output becomes "0", indicating that it is rotating in the reverse direction. Also, counter 5
1, its count value is down, and its output 2SB and LSB change sequentially from 00 to 11, 10, 01, and both rotary switches 31 and 4
The movable contacts 31 ₀ and 41 ₀ of 1 rotate in a direction opposite to that shown in FIG. By reversing the rotary switch 41, as shown in FIG. 5A, the four-phase sine wave signals are changed to the order of reverse rotation v _d →v _b →v _c at a timing symmetrical to that of forward rotation. →v _a
is supplied to the zero crossing point detection circuit 42 according to
As shown in Figure B, each zero-crossing point is detected at a timing symmetrical to the forward rotation. Also,
Since the rotary switch 31 is reversed one step later than the rotary switch 41, the zero-crossing point of each sine wave signal is not transmitted to the detection circuit 32.

In addition, in the above-mentioned embodiment, the magnetoelectric converter 1
The sine wave signals v _a and v _b of 2 a and 12 b are added and subtracted only once to obtain a total of four sine wave signals v _a to v _d to detect the position of the capstan motor 2. The position of the capstan motor 2 may be detected by adding or subtracting these sine wave signals v _a to v _d as appropriate to obtain more sine wave signals having different phases. In this case, only the number of fixed contacts of both electronic switches 31 and 41 and the number of bits of the switching control signal _Ss need to be increased, and compared to the previously proposed device, it is easier to cope with multi-phase sine wave signals. .

Further, in the above-described embodiments, the case where the rotating device is a capstan motor has been described, but the present invention can be widely applied to other rotating devices whose rotational position needs to be detected with high accuracy.

H. Effects of the invention As detailed above, according to the invention, multiphase sine wave signals are selected in a predetermined order to detect zero-crossing points, thereby preventing malfunctions due to mixed noise, and A rotational position detection device for a rotating device that can quickly detect the rotational direction of the rotating device based on point detection outputs is obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the rotational position detecting device for rotating equipment according to the present invention, and FIGS. 2 to 5 are time charts for explaining the operation of the embodiment of the present invention. Fig. 6 is a block diagram showing an example of the configuration of a conventional rotational position detection device for rotating equipment, Figs. 7 and 8 are waveform diagrams for explaining the operation of the conventional example, and Fig. 9 is a diagram showing an example of the configuration of a rotating equipment according to an existing proposal. FIG. 10 is a block diagram showing an example of the configuration of a rotational position detecting device, and is a time chart for explaining the operation of the already proposed device. 31 and 41 are signal selection means, 32 and 42 are zero-cross point detection circuits, 51 is an up-down counter, and 52 is an RS flip-flop.

Claims (1)

[Claims for Utility Model Registration] A rotating body connected to a rotating shaft of a rotating device has a phase difference of 90 degrees that changes with rotation.
and first and second sine wave signal extraction devices for extracting the second sine wave signals;
By adding and subtracting the first and second sine wave signals, there is a zero crossing point having a predetermined phase interval between the zero crossing points of the first and second sine wave signals, and the period is the same as that of the first and second sine wave signals. a sine wave signal synthesis circuit for forming a plurality of synthesized sine wave signals equal to two sine wave signals; and a first signal selection means for selecting the plurality of composite sine wave signals in a first order in which these signals are sequentially arranged with the predetermined phase interval, and the rotating device rotates in the opposite direction. When the selection control signal selects the first and second sine wave signals and the plurality of composite sine wave signals,
a second signal selection means that selects in a second order opposite to the order of the signal selection means; and first and second zero-crossing point detection that detects respective zero-crossing points of the outputs of the first and second signal selection means. a first circuit that gates each of the outputs of the first and second zero-crossing point detection circuits by a gate signal;
and a second gate circuit; a counter that counts the output signals of the first and second gate circuits and outputs a rotational position signal of the rotating device; a delay unit that outputs a selection control signal; a gate signal generation circuit that outputs the gate signal that closes the first and second gate circuits during a predetermined period immediately after the transition on the output side of the counter; and a rotational direction detection circuit that detects the rotational direction of the rotary device based on the output of the second gate circuit.