JPH0511889B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to an improvement of a rotation speed detector using a magnetic bubble element, which is used for position control of NC machine tools and robots.

《Prior art》 Conventionally, an example of this type of rotation speed detector is:
There is a device that the applicant of the present application has already filed as Japanese Patent Application No. 81901/1983. FIG. 5 is a configuration diagram showing an outline of this rotation speed detector. In the figure, a permanent magnet 2 rotates around a rotating shaft 1 to generate a driving magnetic field for a magnetic bubble element 3, and sequentially transfers magnetic bubbles in accordance with the rotation of the driving magnetic field. The number of rotations of the rotating shaft 1 is detected from the position of the magnetic bubble on the transfer pattern in the magnetic bubble element 3. Although a rotation speed detector with such a configuration has the advantage of operating even when the power is cut off, it has a large number of transfer elements, resulting in poor manufacturing yields, a large chip size, and a signal processing circuit. There were drawbacks such as complexity.

Figure 6 shows a rotation speed detector invented in order to solve the above problems.
This is a block diagram showing the main part of the device already filed as No. 221671, and shows a magnetic bubble transfer means that transfers magnetic bubbles independently of a permanent magnet. The magnetic bubble transfer means 4 generates a second rotating magnetic field by driving a drive coil 41 that generates a drive magnetic field in the X direction and a drive coil 42 that generates a magnetic field in the Y direction with currents that are 90 degrees out of phase. . FIG. 7 is an explanatory diagram for explaining the operation on the transfer loop D, which is the transfer pattern of the magnetic bubble element 3 in FIG. 6, where D1 is a magnetic bubble generation pattern, D2
is a magnetic bubble detector, and P0 to P7 are magnetic bubble transfer positions when the driving magnetic field vector H by the permanent magnet is directed in the direction shown in the figure. By driving the magnetic bubble transfer means 4, the bubble detector D
If 2 continues to transfer until it detects a magnetic bubble,
From the transfer amount at that time, the original position of the magnetic bubble, that is, the rotation speed of the rotating shaft 1 up to that point can be calculated. According to the rotation speed detector having such a configuration, the number of transfer elements constituting the transfer loop can be reduced, the yield during manufacturing can be improved, and the number of magnetic bubble detectors can be reduced to 1.
For one thing, the signal processing circuit can be simplified, and the chip size of the magnetic bubble element can be reduced to reduce manufacturing costs.

<Problems to be Solved by the Invention> However, in the method of writing one magnetic bubble in one transfer element loop as in the above configuration,
For example, in order to detect a magnetic field of 1000 rotations, it is necessary to construct a 1000-bit transfer element loop and generate a magnetic field of 1000 rotations with a coil. For this reason, the number of bits in the transfer element is large, resulting in poor yield and
As shown below, there was a problem that the transfer time required for detection was too long. In other words, in a normal bubble memory, bubbles are transferred at a frequency of 100 kHz (10 μsec period), so in the above case, 10 μsec×1000=10 msec is required for rotation detection. However
If a four-pole magnetized rotating magnet is attached to a shaft that rotates at 3000 rpm, the magnetic field generated by the magnet will rotate once every 10 msec, so rotation detection will not be able to keep up with the rotation of the magnetic field.

The present invention has been made to solve these problems, and aims to realize a rotation speed detector that can improve yield during manufacturing and shorten detection time.

<Means for Solving the Problems> The present invention generates a driving magnetic field for a magnetic bubble element by a permanent magnet attached to a rotating shaft, etc., and moves the driving magnetic field from the position of the magnetic bubble on the transfer pattern in the magnetic bubble element to the rotating shaft. This is related to a rotation speed detector designed to detect the _rotation speed _of Form multiple transfer loops with the number of transfer elements,
A magnetic bubble detector is disposed in each of the transfer loops, and magnetic bubble transfer means is provided for transferring magnetic bubbles on each of the transfer loops independently of the permanent magnet, and each transfer loop has a magnetic bubble detector of 2 ⁿⁱ ≧Ni. ＞
Write the ni-order memory wheel pattern that satisfies 2 ^ni-1 (where i = 1, 2, ...) depending on the presence or absence of magnetic bubbles, and when the maximum value of n ₁ , n ₂ , ... is nm, the magnetic bubble transfer is performed. The present invention is characterized in that the number of rotations of the rotating shaft or the like is detected from a combination of signal train patterns generated in the output of each of the magnetic bubble detectors when transfer is performed nm times.

<<Effect>> According to the above configuration, the selected integers N ₁ , N ₂ ,
Since ... has no common divisor, the combination of output signal patterns in each detection loop is an integer N ₁ ,
There are only the products of N ₂ ,... (least common multiple N ₁ ×N ₂ ×...), and many rotational speeds can be easily detected. Therefore, the number of transfer elements constituting the transfer loop can be reduced, and the above objective can be achieved.

"Example" The present invention will be explained in detail below using the drawings.

FIG. 1 is a block diagram showing an embodiment of a rotation speed detector according to the present invention, and shows an example of a detection loop constituting a transfer pattern. The example shown in the figure is
Two integers N ₁ = 8 and N ₂ = 7 are selected as integers that have no common divisors, and are shown in Figure 1a.
corresponds to the integer 8, and the maximum detected rotation speed is N ₁ = 8
FIG. 1b shows a detection loop in which the maximum detected rotational speed is N ₂ =7 corresponding to the integer 7. In the figure, the same parts as in FIG. 7 are designated by the same reference numerals. D and E are transfer loops consisting of eight and seven transfer elements, respectively, D1 and E1 are patterns for generating magnetic bubbles, and D2 and E2 are magnetic bubble detectors. The details of the operation will be described later, but to give an overview, the 6th
A magnetic bubble is transferred three times by the magnetic bubble transfer means 4 having the same configuration as that shown in the figure, and the position of the magnetic bubble is detected from the combination of time-series signal patterns generated in the outputs of the magnetic bubble detection means D2 and E2. After detection, the magnetic bubble is transferred three times in the opposite direction by the magnetic bubble transfer means 4 and returned to its original state.

The detection loop shown in FIG. 1a is similar to that in FIG.
The maximum detected rotational speed is 8 (=2 ³ ), and the transfer loop D is composed of eight transfer elements. The magnetic bubble detector D2 has the same configuration as that shown in FIG. 7, but the position of the magnetic bubble generation pattern D1 is at the position P7 in FIG. Further, on the transfer loop D, an 8-digit bit pattern (01110100) determined by the memory wheel theorem is formed depending on the presence or absence of magnetic bubbles.

In addition, in the detection loop shown in FIG. 1b,
Since the maximum detection rotation speed N is 2 ² <N (=7) ≦ 2 ³ , the transfer loop E is composed of seven transfer elements, and one magnetic bubble detector E2 is installed in the transfer loop E. It is located. Further transfer loop E
On the top, a seven-digit bit pattern (0110100) determined by the memory wheel principle is formed depending on the presence or absence of magnetic bubbles.

Generally speaking, an S ⁿ type memory wheel is one in which S ⁿ types of symbols are arranged around the wheel.
When the rotor touching the next n symbols makes one revolution, there is a permutation of n symbols from the S type symbol.
It refers to something that appears every time. Figure 2 shows an example of a ^23- inch memory wheel. When the binary bit pattern (0, 1) is arranged as shown in the figure,
The 3-digit binary pattern signal obtained according to the rotation of the rotor R takes eight different patterns depending on the position (rotation angle) of the rotor R. It can be seen that the position can be discriminated.

In the detection loop shown in FIG. 1a, during detection, the magnetic bubble transfer means 4 transfers magnetic bubbles three times to form a rotor R, and the transfer of magnetic bubbles corresponds to the rotation of the rotor R due to the driving magnetic field of the magnet. There is. Therefore, a series of pattern signals obtained chronologically from the magnetic bubble detector D2 corresponds to the number of transferred magnetic bubbles, and the number of rotations of the driving magnetic field (rotating shaft, etc.) is detected from this pattern signal. be able to.

In addition, in the detection loop shown in Fig. 1b, the number of transfer elements, that is, the number of digits of the bit pattern, is 7, but if the bit pattern shown in Fig. 1a is modified, a bit pattern based on the memory wheel principle can be obtained. Can be easily formed.

Figures 3 and 4 show the relationship between the rotational speed of the drive magnetic field and the movement state of the bit pattern on the transfer loop. has been detected by. That is, in the magnetic bubble transfer state shown in FIG. 1 (state of rotation speed 2), when the magnetic bubble transfer means 4 transfers three times clockwise in the figure, the output signal sequence of the magnetic bubble detector D2 becomes "110". Therefore, the output signal sequence of magnetic bubble detector E2 is “101”
becomes. Thereafter, the magnetic bubble transfer means 4 transfers the bubble in the opposite direction three times to return to the original position. Further, when the driving magnetic field rotates one more rotation, the pattern signal of D2 changes to "101" and the pattern signal of E2 changes to "010", indicating a state where the number of rotations is 3.

In this way, if unit detection loops are formed using the memory wheel principle with the integers 8 and 7 as the maximum detection rotation speeds N ₁ and N ₂ , respectively, each detection loop will respond to the rotation of the drive magnetic field. A constant pattern signal is output with cycles of 3 rotations and 7 rotations. Therefore, since the integers 8 and 7 do not have a common divisor, there are 56 combinations of these output signals, which are equal to the least common multiple of the two integers, and we need to compare the states of these output signals. For example, it will be possible to detect rotational speeds up to 56.

Here, the total number of transfer elements constituting the two unit detection loops is 15. Incidentally, if a transfer pattern for detecting 56 rotational speeds is constructed using the conventional method as shown in FIG. 7, 56 transfer elements will be required. In other words, according to the above embodiment, the number of transfer elements can be significantly reduced, yield during manufacturing can be improved, and the chip size of the magnetic bubble element can be reduced to reduce manufacturing costs. . Furthermore, since the number of transfers may be 6 (=3×2) instead of 56 transfer elements, the transfer time can be shortened, and as a result, the detection time can be shortened. Furthermore, the effect is even more remarkable when the number of transfer elements is larger. For example, two detection loops, one 63 bit and one 62 bit, can be formed to
Considering the case of detecting 3906 rotations, 2 ⁶ ≧63＞
From 2 ^6-1 and 2 ⁶ ≧ 62 > 2 ^6-1 , configure a memory wheel of order n = 6 in both transfer loops to obtain 6 × 2 =
It is only necessary to perform the transfer 12 times (transfer time = 0.12 msec when transferring with a 100 kHz coil magnetic field).
In contrast, in the conventional method, the number of transfer elements is 3906, the number of transfers is 3906, and the transfer time is 39.06 msec.

Furthermore, since it is synchronized with the rotating magnetic field of the magnetic bubble transfer means, detection with a good S/N ratio can be performed.

In addition, in the above explanation, two integers 8,
Although the case where 7 is selected and 56 rotational speeds are detected is illustrated, the assumed number of integers is not limited to two. For example, assuming an arbitrary number of integers N ₁ , N ₂ , ..., the total number of transfer elements is the sum of these integers N ₁ , N ₂ , ... (N ₁ + N ₂ + ...), the detectable rotation number is the product of these integers N ₁ , N ₂ ,... (N ₁ ×
N ₂ ×…). Also in this case, each integer N ₁ ,
The method of configuring a detection loop with N ₂ ,... as the maximum detection rotation speed is 2 ⁿⁱ ≧Ni＞2 ^ni-1 (where i=1, 2,
), each transfer loop is configured with Ni transfer elements, and is determined by the memory wheel theorem.
A Ni-digit bit pattern may be formed on the transfer loop depending on the presence or absence of magnetic bubbles. n ₁ , n ₂ ,
When the maximum value of ... is nm, transfer is performed nm times by the magnetic bubble transfer means, and at this time, the signal string pattern generated in the output of each magnetic bubble detector is detected,
The rotational speed of the drive magnetic field is detected from the combination. Furthermore, by performing the transfer nm times in the reverse direction, a rotation speed detector with the maximum detected rotation speed N=(N ₁ ×N ₂ × . . . ) can be realized with only 2 nm transfers.

In the above embodiment, the magnetic bubble transfer means performs transfer nm (=8) times for detection, and then transfers the magnetic bubble in the opposite direction nm times to return the magnetic bubble to its original direction. may be omitted. That is, instead of performing nm reverse transfers, if the signal processing circuit subtracts nm from the rotation speed each time it is detected, the same rotation speed output can be obtained in 1/2 the transfer time.

In addition, by measuring the magnetic field of the rotating magnet and generating an offset magnetic field in a coil (which can also serve as a magnetic bubble transfer means) to cancel this field, the magnetic resistance element that constitutes the magnetic bubble detector is prevented from being saturated. By doing so, more stable rotation speed detection can be performed.

Furthermore, the rotation speed detector of the present invention is suitable for realizing a multi-rotation encoder by combining it with an encoder capable of obtaining an absolute measurement output. That is, the rotation speed of the rotating shaft, etc. is detected by the rotation speed detector of the present invention, and the
By detecting the rotation angle with an encoder, even if the power is cut off during measurement,
It is possible to realize a multi-rotation encoder that can always obtain absolute measurement output.

<<Effects of the Invention>> As described above, according to the present invention, it is possible to realize a rotation speed detector with a simple configuration that can improve the yield during manufacturing and shorten the detection time.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the rotation speed detector according to the present invention, FIG. 2 is an explanatory diagram for explaining the principle of the memory wheel, and FIGS. An explanatory diagram for explaining the operation, FIG. 5 is a block diagram showing a conventional example of a rotation speed detector, FIG. 6 is a main part block diagram showing a prior art of a rotation speed detector, and FIG. It is an explanatory diagram for explaining operation of a figure device. 1... Rotating shaft, 2... Magnet, 3... Magnetic bubble element, 4... Magnetic bubble transfer means, D, E... Transfer loop, D2, E2... Magnetic bubble detector, P
0 to P7...Position of magnetic bubble.

Claims (1)

[Claims] 1. A permanent magnet attached to a rotating shaft, etc. generates a driving magnetic field for a magnetic bubble element, and the rotation speed of the rotating shaft, etc. is detected from the position of a magnetic bubble on a transfer pattern in this magnetic bubble element. In the rotation speed detector configured to have the following configuration, a plurality of transfer loops are formed in which the number of transfer elements is two or more integers N ₁ , N ₂ , ... that do not have a common divisor as the transfer pattern, and each of the above A magnetic bubble detector is disposed in the transfer loop, and a magnetic bubble transfer means for transferring the magnetic bubbles on each transfer loop independently of the permanent magnet is provided, and in each transfer loop, 2 ⁿⁱ ≧Ni>2 ^{The ni-th memory wheel pattern satisfying ni-1} (where i=1, 2, ...) is written depending on the presence or absence of magnetic bubbles, and when the maximum value of n ₁ , n ₂ , ... is nm, the magnetic bubble transfer means A rotation speed detector characterized in that the rotation speed of the rotation shaft or the like is detected from a combination of signal train patterns generated in the output of each of the magnetic bubble detectors when transfer is performed nm times.