JPH0378619A - Absolute-value pulse encoder - Google Patents

Abstract

PURPOSE:To realize a compact encoder by a construction wherein Wiegand wires disposed at positions being different in a phase by 90 degrees in relation to a rotating magnetic field are connected to two coils of a magnetic bubble domain memory element which intersect at right angles each other. CONSTITUTION:Two Wiegand wires 3X and 3Y are disposed at positions being different in a phase by 90 degrees in relation to a rotating magnetic field generated by a permanent magnet 2 of a rotating shaft 1. They are connected to two coils 6X and 6Y for bubble transfer of a magnetic bubble domain memory element 2 intersecting at right angle each other, through the intermediary of selector switches 4X and 4Y, respectively. As the result, bubbles in a bubble transfer loop of the magnetic bubble domain element 5 are transferred one by one through the loop every time when a pulse flows through each coil, and the number of rotations of the rotating shaft 1 and the position of rotation thereof can be detected from the position of the bubble in the loop. Therefore, the element 5 necessitating a bias magnetic circuit or the like can be disposed separately from a permanent magnet 8 and a compact construction can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an encoder that detects the rotation speed and rotation angle using a magnetic bubble element, and in particular, the present invention relates to an encoder that detects the rotation speed and rotation angle using a magnetic bubble element. The present invention relates to an absolute value encoder that detects using a magnetic bubble element.

BACKGROUND ART A permanent magnet is attached to a rotating shaft, and as the rotating shaft rotates, a rotating magnetic field generated by the permanent magnet causes bubbles in a bubble transfer loop of a magnetic bubble memory element to be transferred, and the bubble position in this bubble transfer loop is used to transfer bubbles. A rotational speed detector adapted to detect the rotational speed and rotational position of the rotating shaft is disclosed in Japanese Patent Application Laid-open No. 62-238414 and Japanese Patent Application Laid-open No. 63-7.
This is known from Japanese Patent No. 5617 and the like.

Problems to be Solved by the Invention A magnetic bubble memory element requires a bias magnetic circuit that applies a bias magnetic field perpendicular to the surface of the memory element in order to hold the bubbles stored in the memory element so that they do not disappear. Generally, a pair of permanent magnets are arranged above and below the surface of the memory element, and the permanent magnets apply a bias magnetic field in a direction perpendicular to the surface of the memory element.

Furthermore, it is necessary to magnetically shield the magnetic bubble memory element itself using permalloy or the like in order to prevent bubbles within the memory element from being transferred due to a disturbance magnetic field generated from the outside.

On the other hand, in order to transfer the bubbles in the bubble memory element within the transfer loop using the rotating magnetic field generated from the permanent magnet attached to the rotating shaft, the bubble memory element is Detectable position,
That is, it is necessary to arrange it at a position close to the rotating permanent magnet.

Therefore, it is necessary to spread the bias magnetic field permanent magnet and the shielding member at an appropriate distance from the bubble memory element so that the bubble memory element can detect the rotating magnetic field from the permanent magnet. If the bias magnetic field permanent magnets and shielding members are arranged at intervals in this way, there is a disadvantage that the volume of the encoder itself for detecting the rotational position becomes large, which is a disadvantage in the design of machines such as machine tools to which the encoder is installed. Unfavorable.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a compact absolute value pulse encoder using a magnetic bubble memory element.

Means for Solving the Problems The absolute value pulse encoder of the present invention includes a permanent magnet attached to a rotating shaft and a rotating magnetic field generated by the permanent magnet that can be detected and arranged at a position 90 degrees out of phase with respect to the rotating magnetic field. A magnetic bubble memory having at least one bubble transfer loop, which includes two Uigant wires, a bias magnetic circuit, and two orthogonal coils for bubble transfer, and at least one bubble is written in the loop. The bubbles in the bubble transfer loop are transferred by inputting the outputs of the Wigand wires to the corresponding coils, and the rotational speed and rotational position of the rotating shaft are controlled depending on the bubble position in the bubble transfer loop. The above problem was solved by detection.

In one cycle of the rotating magnetic field, the working Wigand wire receives 18
Pulses with different polarities are generated at positions with different 0 degree phases. Since the Wigand wires are placed at positions that are 90 degrees out of phase with the rotating magnetic field, a pulse is generated from the two Wigand wires each time the rotating magnetic field advances by 90 degrees during one cycle of the rotating magnetic field. That will happen. Therefore, if the output of one Wigand wire is input to one of the perpendicular coils for bubble transfer, for example, the coil in the X-axis direction, and the output of the other Wigand wire is input to the coil in the Y-axis direction, After a positive pulse from one Wigand wire flows through the axial coil, when the 90 degree rotational magnetic field advances, a positive pulse flows through the Y axis direction coil, then the 90 degree rotation and the X axis direction coil. A negative pulse flows through the coil in the Y-axis direction, and when it moves further 90 degrees, a negative pulse flows through the coil in the Y-axis direction. As a result, the bubbles in the bubble transfer loop of the magnetic bubble memory element are transferred one by one through the loop each time a pulse flows through each coil, and the rotation speed and rotational position of the rotating shaft are determined by the bubble position in this loop. can be detected.

Example FIG. 1 is a configuration diagram of an embodiment of the present invention.

A permanent magnet 2 is attached to a rotating shaft 1 of a motor, etc.
In the vicinity of the permanent magnet 2, a rotating magnetic field generated from the permanent magnet 2 that rotates with the rotation of the rotating shaft 1 can be detected.
In addition, the Wigant wires 3X and 3Y are arranged at positions 90 degrees out of phase with the rotating magnetic field.

One end of the Wigant wires 3X, 3Y is grounded, and the other end is connected to two orthogonal bubble transfer coils 6X, 6Y of the magnetic bubble memory element 5 via changeover switches 4X, 4Y, respectively.

Hereinafter, one coil 6X will be referred to as an X coil, and the other coil 6Y will be referred to as a Y coil. The X coil 6X winds the bubble chip 7 of the magnetic bubble memory element 5 in the X-axis direction, and
The coil 6Y is wound around the bubble chip 7 in the Y-axis direction.

Further, the bubble chip 7 has at least one bubble transfer loop, and one bubble is written in the bubble transfer loop by a known bubble writing means (not shown). Further, 8, 8 is a pair of permanent magnets arranged above and below the surface of the bubble chip 7 in parallel with the surface of the bubble chip 7, and holds the bubbles in the bubble chip so that they do not disappear due to the magnetic field generated from the permanent magnets. The permanent magnet constitutes a bias magnetic circuit.

In addition, 9 is for reading the bubble position, the above-mentioned X coil 6X
, is a reading rotating magnetic field generator for passing current through the Y coil 6Y and generating a rotating magnetic field, and the changeover switches 4X, 4
Y connects the coils 6X, 6Y to the read rotating magnetic field generator. Although not shown, the magnetic bubble memory element 5 is provided with detection means for detecting bubbles as in the conventional case.

Figure 2 (A) shows the waveform of the rotating magnetic field generated by the permanent magnet 2 that rotates with the rotating shaft 1, where 1-OX is the waveform of the rotating magnetic field for the Wigant wire 3X, and 10Y is the waveform with a 90 degree phase lag. This is the waveform of the rotating magnetic field for the Wigant wire 3Y, and the Wigant wires 3X and 3Y are
As shown in figures (b) and (c), rotating magnetic field 10X, IOY
It outputs positive and negative balance alternately every time it advances 180 degrees. As a result, Wigand wires 3X and 3Y are 90
Since the permanent magnets 2 are arranged with a phase shift of 9 degrees,
Every time the wire rotates by 0 degrees, a plus or minus pulse is output from either one of the Wigand wires 3X and 3Y.

Changeover switches 4X and 4Y are Uigant wires 3X and 3Y.
When the rotating shaft 1 and the permanent magnet 2 rotate while connected to the side, for example, a positive pulse is output from the Wigand wire 3x, and when a current flows through the X coil 6x, the bubble transfer loop of the bubble chip 7 The bubble is transferred in the X-plus direction. Next, when the permanent magnet 2 rotates 90 degrees, a positive pulse is output from the Wigand wire 3Y.
The coil 6Y is excited and the bubble is transferred in the Y-plus direction. Furthermore, when the permanent magnet 2 rotates 90 degrees, a negative pulse is output from the Wigant wire 3X, and the X coil 6X
is excited and transfers the bubble in the X-minus direction. Then, when the permanent magnet 2 rotates another 90 degrees, a negative pulse is output from the Wigant wire 3Y, causing the bubble to move to Y.
Transfer in the negative direction. Hereinafter, as the permanent magnet 2 rotates, the Wigand wires 3X and 3Y are sequentially added,
Negative pulses are output alternately, and the bubbles in the bubble chip 7 of the magnetic bubble memory element 5 are sequentially transferred. As a result, the bubble position within the bubble transfer loop indicates the rotational speed and rotational position (angle) of the rotating shaft 1.

When detecting the rotational speed and rotational position (angle) of the rotating shaft 1, the changeover switches 4X and 4Y are switched to the reading rotating magnetic field generator 9 side, and the reading rotating magnetic field is generated until a bubble is detected by a bubble detection means (not shown). Activate device 9, X, Y coil 6X.

6Y generates a rotating magnetic field to transfer bubbles. The number of rotations and the rotational position of the rotating shaft 1 can be detected based on the number of times the bubble is transferred by the reading rotating magnetic field generator 9.

In this embodiment, the number of magnetic poles of the permanent magnet attached to the rotating shaft 1 was two, a pair of N pole and S pole. It may be arranged so that the polarity of the magnetic pole changes alternately between pole and south pole, and in this case, the two Wigand wires are arranged so that the phase of the resulting rotating magnetic field is shifted by 90 degrees. to be placed.

Effects of the Invention The present invention requires only a Wigant wire to be placed near the permanent magnet attached to the rotating shaft, and magnetic bubble memory elements that require a bias magnetic circuit or magnetic shield can be
There is no need to place it near the permanent magnet attached to the rotating shaft, and it can be placed at the optimal position for the design, making it easier to design machines such as NC machine tools that require an absolute value pulse encoder. I can do it.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of an embodiment of the present invention, Figures 2 (A), (
B) and (C) are explanatory diagrams of the rotating magnetic field generated from the permanent magnet and the output pulse of the Wigand wire in the same embodiment. 1... Rotating shaft, 2... Permanent magnet, 3X, 3Y...
Wigant wire, 4X, 4Y...switch switch, 5
...Magnetic bubble memory element, 6X, 6Y... Coil for bubble transfer, 7... Bubble chip, 8... Permanent magnet for bias, 9... Reading rotating magnetic field generator, 10
X, IOY...Rotating magnetic field. (2 others) Hun

Claims (1)

[Claims] A permanent magnet attached to the rotating shaft, two Wigant wires that can detect the rotating magnetic field generated by the permanent magnet and are placed at positions 90 degrees out of phase with respect to the rotating magnetic field, and a bias magnetic circuit and bubble transfer. a magnetic bubble memory element having at least one bubble transfer loop having two orthogonal coils, and at least one bubble written in the loop, and transmitting the output of the Wigand wire to the corresponding coil. An absolute value pulse encoder that transfers bubbles in a bubble transfer loop by inputting the respective inputs into the bubble transfer loop, and detects the rotational speed and rotational position of a rotating shaft based on the bubble position in the bubble transfer loop.