JPH051922A - Rotation speed detector - Google Patents

Abstract

PURPOSE:To read a part of the bit pattern of a magnetic valve without using a read coil by rotating a magnetic valve chip to move each magnetic valve on a transfer element loop. CONSTITUTION:A holding body 5 is rotated by rotating a motor 75. By the rotation of the holding body 5, a rotating magnetic field by the magnetic field from a ring magnet 1 is added to a magnetic valve chip 10. Thus, each magnetic valve is transferred on a transfer element loop provided on the chip 10 and successively passed through a magnetic valve detecting element. The bit pattern based on the pass of the magnetic valve is detected followed by waveform shaping, and outputted as a pulse signal. By arithmetically processing the bit pattern, a cumulative rotating speed is obtained. When the detection of the magnetic valve is ended, the rotation of the motor 75 is reversed, and the holding body 5 is rotated reversely and returned to the position before reading the bit pattern. Thus, the following rotation of a shaft 2 is never influenced by the measurement of the cumulative rotating speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotational speed detector using a magnetic bubble, and more particularly to an improvement of a mechanical method for reading the rotational speed.

[0002]

2. Description of the Related Art As for a rotational speed detector using a magnetic bubble, the applicant of the present invention has a Japanese Patent Application No. 61-81901 (referred to as a prior example 1) and a Japanese Patent Application No. 62-212208 (referred to as a prior example 2). Etc., and its principle is widely known. FIG. 4 is a diagram showing the principle of operation of the rotation speed detector using magnetic bubbles in the above-mentioned prior art, and FIG. 5 is a pattern example diagram of transfer element loops provided on the magnetic bubble chip of FIG.

In FIG. 4, the magnetic bubble chip 10 is made of a material that generates magnetic bubbles. Magnetic bubble
By applying a perpendicular magnetic field of an appropriate strength, it is generated in a cylindrical shape in a perpendicular magnetic film epitaxially grown on GGG (gadolinium-gallium-garnet) by several μm. On the magnetic bubble chip 10, a transfer element 31 made of thin film permalloy is formed in a loop shape (see FIG. 5).
When a rotating in-plane magnetic field is applied, the magnetic bubble is transferred by being attracted to the magnetized transfer element. Although one transfer element loop is shown in FIG. 5, a plurality of transfer element loops are provided on the actual magnetic bubble chip 10. A magnetic bubble is written in each transfer element loop in a bit pattern based on the "memory wheel principle" as known in the second prior art.

The bias magnet 81 is a set of two magnets, and has a function of applying a constant magnetic field (bias magnetic field) perpendicular to the magnetic bubble chip 10 to hold bubble-shaped magnetic domains.

The read coils 43 and 44 are magnetic bubble elements 1.
It is arranged around 0 as shown in FIG. The read coils 43 and 44 are used when reading the cumulative number of rotations of the rotary shaft to which the ring magnet 1 is attached, and a rotating magnetic field is generated by passing an alternating current through the coils to transfer magnetic bubbles.

The ring magnet 1 is a rotating shaft (not shown).
It is a permanent magnet attached to. The ring magnet 1 has an in-plane magnetic field vector H parallel to the magnetic bubble chip 10.
r (= Hx + Hy), and the in-plane magnetic field vector Hr rotates as the rotating shaft rotates.
The magnetic bubble circulates in the transfer element loop with one transfer element / one rotating magnetic field. FIG. 4 is an example of a ring magnet magnetized to have eight poles. In this case, when the rotating shaft makes one rotation, the magnetic bubbles move by four transfer elements 31.

In each transfer element loop shown in FIG. 5, magnetic bubbles having a special arrangement pattern based on the "principle of the memory wheel" described in the prior example 2 are written. The special array pattern is a pattern having the feature that a continuous bit pattern cut out from a certain position in all bit patterns is not the same as a pattern with the same number of bits cut out from any other position. Therefore, it is possible to know the transfer shift amount of the bit pattern in the loop by reading a certain number of continuous bit patterns from a certain position of the transfer element loop.
The reading of the magnetic bubble is performed by the magnetic bubble detector 20 provided in the transfer element loop.

When the ring magnet 1 rotates, the bit pattern of the magnetic bubble circulates on the transfer element loop according to the rotation. The patrol operation is normally performed even when the device of FIG. 4 is stopped by an electric circuit due to a power failure or the like.

When the ring magnet 1 makes, for example, 10 rotations in a power failure state, the magnetic bubble moves to a position corresponding to the 10 rotations. When the power supply is restored, the reading coils 43 and 44 are used in the conventional device to measure how many rotations the ring magnet 1 has made.
Is operated to generate a rotating magnetic field, and the position of the magnetic bubble is sequentially moved by, for example, 10 bits. Therefore,
Since 10 bits of magnetic bubbles pass through the magnetic bubble detector 20 provided on the transfer element loop, ten time-series bit patterns are read out, and a ring magnet is read from the patterns by the principle of the memory wheel. It is possible to know the cumulative rotation speed of.

[0010]

The conventional rotation speed detector as described above has the following problems. The read coils 43 and 44 are required to measure the cumulative number of revolutions.
Here, the strength of the magnetic field applied from the read coil to the magnetic bubble chip requires considerable accuracy. If this accuracy cannot be satisfied, magnetic bubbles that disappear (or are generated) will appear, and the pattern of the magnetic bubbles will be destroyed, and the device will not operate. In this respect, Japanese Patent Application No. 2-027821
It is described in detail in the issue.

As a countermeasure, in Japanese Patent Application No. 2-027821,
A magnetic bubble chip with a wide operating margin is used. If the homogeneity of the distribution of the magnetic fields generated from the read coils 43 and 44 is not within a certain range, the disappearance / generation of magnetic bubbles will occur in the same manner as described above. This point is
It is described in detail in No. 2-017761.

In Japanese Patent Application No. 2-017761, this problem is solved by manufacturing a read coil with a special winding method. An object of the present invention is to provide a rotation speed detector that solves the above problems by moving a magnetic bubble on a transfer element loop without using a read coil to read a part of the bit pattern. ..

[0013]

In order to solve the above problems, the present invention applies a magnetic field of a permanent magnet mounted on a rotating shaft to a magnetic bubble chip provided with a transfer element loop to form a bit pattern. In a rotation speed detector that moves a magnetic bubble on the transfer element loop and reads a part of the bit pattern to measure the cumulative rotation speed of the rotating shaft, the magnetic field is generated in a plane parallel to the magnetic field generated by the permanent magnet. Rotating means for rotating the bubble chip in one direction and then rotating it in the opposite direction to return it to its original position, and a magnetic bubble detector provided on the transfer element loop for detecting the presence or absence of passing magnetic bubbles, A current supply means for supplying a current from the outside to the magnetic bubble detector in a non-contact manner, and a detection signal transmitting means for transmitting a detection signal of the magnetic bubble detector to the outside in a non-contact manner. For example, when measuring the cumulative rotational speed,
The rotating means is operated to move each magnetic bubble on the transfer element loop, and a current is supplied from the current supply means to the magnetic bubble detector to detect a part of the bit pattern of the magnetic bubble, and the detection is performed. A signal is transmitted by the detection signal transmission means.

[0014]

In the present invention, when measuring the cumulative number of revolutions, the magnetic bubble chip itself is rotated by the rotating means in the plane parallel to the magnetic field generated by the permanent magnet. Therefore, a rotating magnetic field generated by a permanent magnet is applied to the magnetic bubble chip, and the magnetic bubble is transferred on the transfer element loop. As a result, since the magnetic bubble passes through the magnetic bubble detector, the bit pattern of the passed magnetic bubble can be read by the magnetic bubble detector. Further, since signals are exchanged between the magnetic bubble detector and the outside without contact, the structure is simple and long-term reliability is obtained.

Since the magnetic bubble chip is rotated in the opposite direction by the rotating means and returned to the original position, the bit pattern of the magnetic bubble returns to the bit position before reading,
Subsequent rotation of the rotating shaft does not affect the measurement of the cumulative number of rotations.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a rotation speed detector according to the present invention, and FIG. 2 is a block diagram of FIG.

In the conventional device, a rotating coil is used to generate a rotating magnetic field to forcibly transfer magnetic bubbles to read a pattern. The present invention utilizes a ring magnet attached to the rotating shaft instead of the read coil,
By rotating the magnetic bubble tip in a plane parallel to the magnetic field generated by the ring magnet, a rotating magnetic field is obtained and the magnetic bubble pattern is read out.

In FIG. 1, a rotating shaft (hereinafter, simply referred to as shaft) 2 is connected to a motor or the like not shown, and the device of the present invention measures the cumulative number of rotations of the shaft 2.

The ring magnet 1 is a permanent magnet attached to the shaft 2 and rotates with the shaft 2. The ring magnet 1 is magnetized to a plurality of poles as shown in FIG. 1, and rotates with the rotation of the shaft 2 to give an in-plane rotating magnetic field vector to the magnetic bubble chip 10. The operation of transferring this magnetic bubble is the same as that already described in the conventional example of FIG.

The shaft 2 is rotatably attached to the housing 4 via a bearing 3. Reference numeral 5 denotes a holder, which is rotatably attached to the housing 4 via a bearing 6 like the shaft 2. The rotation of the motor 75 is transmitted to the holding body 5 via gears 71, 72, 73 and 74. The rotation shaft of the motor 75 is provided with a stopper (not shown) that sets a rotation angle, and reciprocally rotates. The holding body 5 is accelerated according to the gear ratio of the gears 71, 72, 73, 74, and rotates a plurality of times in the reciprocating direction.

A magnetic bubble chip 10 is attached to the holder 5 via an attaching means (not shown) so as to be positioned on the center of the rotation axis in a plane parallel to the magnetic field generated by the ring magnet 1. Two bias magnets 81 are attached so as to sandwich the chip 10. The bias magnet 81 and the magnetic bubble chip 10 are shown in FIGS.
It has the same configuration and operation as those described in the above.

Further, two coils 11 and 12 are attached to the holder 5 so that the centers thereof coincide with the center of rotation, and these coils 11 and 12 are attached to the magnetic bubble chip 10 as shown in FIG. It is connected to the magnetic bubble detector 20 (see FIG. 5) provided.

On the other hand, the housing 1 has these coils 1
Coil 13, so that it is located near 1, 12 respectively
14 is attached. Oscillation circuit 1 for coil 13
5 is connected, and the electromotive force detection unit 16 is connected to the coil 14.

The output signal of the electromotive force detection unit 16 is applied to the waveform shaping unit 17 and converted into a pulse signal, and the pulse signal is applied to the rotation speed detection unit 18 and output as the cumulative rotation speed.

That is, the exchange of signals between the magnetic bubble detector 20 and the outside is performed in a non-contact manner via these coils 11-14. A controller 19 controls the oscillation circuit 15 and the motor 75.

The operation of measuring the cumulative rotational speed of the shaft 2 by the apparatus of FIG. 1 is as follows. When measuring the cumulative number of rotations, the shaft 2 (ring magnet 1) is stopped. The controller 19 operates the oscillation circuit 15 to supply the coil 13 with an alternating current of frequency f. This allows the coil 1
3 generates a magnetic field whose magnetic flux changes at frequency f. The change in the magnetic flux is applied to the coil 11, and the coil 11 generates an electromotive force by electromagnetic induction to flow an alternating current. The alternating current flows through the magnetic bubble detector 20 to the coil 12. The coil 12 generates a magnetic field whose magnetic flux changes at a frequency f according to the alternating current. The change in magnetic flux is applied to the coil 14, and the coil 14 generates an electromotive force by electromagnetic induction.

If the alternating current applied to the coil 11 is constant, the electromotive force detected by the coil 14 is always constant. By rotating the motor 75 in this state, the holder 5 rotates. Due to the rotation of the holder 5, a rotating magnetic field generated by the magnetic field from the ring magnet 1 is applied to the magnetic bubble chip 10. Therefore, each magnetic bubble 35, 3
, 37, ... Are transferred on the transfer element loop provided in the magnetic bubble chip 10, and the magnetic bubbles successively pass through the magnetic bubble detection elements. The magnetic bubble detection element receives a strong magnetic field when the magnetic bubble passes, and its resistance value decreases.

At this time, the resistance value of the magnetic bubble detecting element is decreased, so that the current flowing through the coil 12 is increased,
The magnetic flux generated by is increased. As a result, the electromotive force generated by the electromagnetic induction in the coil 14 increases as shown in FIG.

As described above, the bit pattern based on the passage of the magnetic bubble can be detected from the waveform of the electromotive force of the coil 14 shown in FIG. The electromotive force waveform of the coil 14 is shaped by a known technique such as half-wave rectification and a comparator to form a pulse signal. Since the bit pattern is read by outputting the passage of the magnetic bubble as a pulse, the cumulative rotation speed can be obtained by processing the bit pattern.

When the detection of magnetic bubbles is completed, the motor 75
Is reversed and the holder 5 is rotated in the opposite direction to return to the position before reading the bit pattern of the magnetic bubble. As a result, the subsequent rotation of the shaft 2 does not influence the measurement of the cumulative rotation speed.

[0031]

As described above, according to the present invention, the following effects can be obtained. (1) Since the bit pattern of the magnetic bubble can be read without requiring a read coil, the problem described in the section of the problem to be solved by the invention can be solved. (2) The circuit part for driving the read coil is not required, and the circuit as a rotation speed detector can be significantly reduced. (3) When the cumulative number of rotations is detected using the read coil, the bit pattern of the magnetic bubble may be destroyed if the shaft 2 rotates during the read operation (the reason is described in Japanese Patent Application No. 2-050544). However, according to the present invention, a magnetic field other than the ring magnet is not newly added, so that there is no such fear. (4) Since the magnetic bubble chip 10 rotates on the spot, there is no dead space, space efficiency is improved, and the size of the entire device can be reduced. (5) Since the signals are exchanged between the magnetic bubble chip and the outside in a non-contact manner, the structure is simple and high reliability can be obtained for a long period of time.

[Brief description of drawings]

FIG. 1 is a configuration example diagram of a rotation speed detector according to the present invention.

FIG. 2 is a block diagram of FIG.

3 is a waveform diagram of an electromotive force of the coil 14 of FIG.

FIG. 4 is a configuration diagram of a conventional example.

5 is an operation explanatory diagram of FIG. 4;

[Explanation of symbols]

 1 Ring Magnet 2 Shaft 3,6 Bearing 4 Housing 5 Holder 10 Magnetic Bubble Chip 11, 12, 13, 14 Coil 20 Magnetic Bubble Detector 71, 72, 73, 74 Gear 75 Motor

Claims (1)

Claims: 1. A permanent magnet mounted on a rotating shaft.
Magnetic bubble chip provided with a transfer element loop
In addition to the
Move on child loop and read part of the bit pattern
Rotation speed detection to measure the cumulative rotation speed of the rotating shaft
In a plane parallel to the magnetic field generated by the permanent magnet
After rotating the magnetic bubble chip in one direction with,
Rotation means for rotating the transfer element back to the original position and the transfer element.
It is installed on the child loop and detects the presence of passing magnetic bubbles.
The magnetic bubble detector that comes out and the magnetic bubble detector that is not connected
A current supply means for supplying a current from the outside by touch,
Detection that transmits the detection signal of the bubble detector to the outside without contact
A signal transmission means, when measuring the cumulative number of revolutions,
By operating the rotating means, each magnetic bar on the transfer element loop is
And move the bull to the magnetic bubble detector.
Magnetic bubbles generated by supplying current from the current supply means
Part of the bit pattern of the
It is characterized in that the signal is transmitted by the output signal transmission means.
Rotation speed detector.