JP3423789B2 - Rotation direction detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation direction detecting device, and more particularly to a device for detecting the rotation direction of a rotating body such as a gear or a rotating shaft.

[0002]

2. Description of the Related Art As a device for detecting the rotating direction of a rotating body such as a gear or a rotating shaft, a detecting element (for example, a magnetoresistive element such as a Hall element) that generates a sinusoidal AC waveform according to the rotation of the rotating body is used. ) Is magnetically and temporally sequentially coupled with the detection member, such as a permanent magnet or a magnetic member, provided on the surface of the rotating body to be measured, and 90 Disposing in different phases, and determining the rotation direction based on the generation order of the outputs of the two detection elements or based on the mutual relationship between the polarity of the output difference between the two detection elements and the output polarity of each detection element. Is known (for example, JP-A-2-140679).

[0003]

The above-mentioned conventional technique has a problem that it lacks versatility because the positional relationship between the two detection elements is limited. For example, in the case where the rotation direction is detected based on the outputs of the two detection elements and the output difference is converted into a digital signal to detect the rotation speed as well, the respective outputs are set to 180 in order to increase the output difference. It is desirable to dispose the two detection elements so that there is a phase difference of 1 degree, but if this is done, there will be no difference in the generation order of the outputs, and it will be impossible to determine the rotation direction. In addition, under the constraint that the two detection elements must be arranged in phases that differ by 90 degrees, for example, the arrangement interval of the detection elements must be changed so as to match the pitch of the gears, so the rotation direction detection device can be set in advance. There is a problem that it is difficult to assemble and share it, and the cost tends to increase.

An object of the present invention is to solve the above problems and arrange two detecting elements so that the output of each of them has a phase difference of 180 degrees even when the pitch of gears changes, etc. It is an object of the present invention to provide a rotation direction detection device that can accurately detect the rotation direction even when the detection is facilitated.

[0005]

A rotation direction detecting device is magnetically coupled with a detection member provided on a surface of a rotating body to be measured along a rotation locus of the detecting member and sequentially in time. The first and second detection elements arranged, and the above-mentioned 2
A third detection element arranged in the middle of the two detection elements, a difference calculation means for calculating the difference between the outputs of the first and second detection elements, and a timing signal by detecting that the sign of the difference is inverted. And the level of the output of the third detection element at the time when the timing signal is generated are compared with a reference value, and according to the comparison result, the rotating body to be measured of the object to be measured is in accordance with a predetermined reference. The rotation direction determining means generates a signal indicating the rotation direction. It is not necessary to have a specific phase relationship between the arrangement intervals of the two detection elements located at both ends, that is, the arrangement intervals of the first and second detection elements and the detection members.

[0006]

When the rotating body to be measured rotates, the detecting magnetic member provided on the surface of the rotating body magnetically couples to the first, third, and second detecting elements in this order or in the reverse order, and each detection is performed. A sinusoidal output is generated at the element. By measuring whether or not the level of the output of the central detection element when the polarity of the difference between the outputs of the first and second detection elements at both ends is reversed is greater than a reference value (for example, 0), The rotation direction of the target rotating body can be known.

[0007]

1 is a block diagram showing the structure and function of one embodiment of the present invention. FIG. 2 is a flow chart showing the operation of the above-mentioned embodiment, and FIG. 3 is a waveform diagram of the signal generated in each detecting element. As shown in FIG. 1, one or a plurality of (rotational) detection members 11 made of a permanent magnet or a magnetic material are provided on the outer periphery of the rotating body 10, and face each other and rotate the detection members. The three Hall elements 13a ...
13c is fixedly arranged. Hall elements 13a, 13
The outputs of c and 13b are read by the signal processing determination device 15 (step S1 in FIG. 2). The signal processing determination device 15 includes a difference calculation unit 15A, a sign inversion detection unit 15B, and a level determination unit 1
5C, and a rotation direction determination unit 15D. The difference calculation unit 15A detects the difference (A−) between the outputs of the Hall elements 13a and 13b.
B) is calculated (step S2), and the sign inversion detector 15B is calculated.
Detects that the sign of the difference (AB) is inverted from positive to negative (step S3). The level determination unit 15C determines whether the level of the output C of the hall element 13c at the time of detecting the sign inversion is high or low (step S4), and the rotation direction determination unit 15D supplied with the determination result determines a predetermined reference. A signal ACB (direction of arrow P) or BCA (direction of dotted arrow Q) indicating the rotation direction is output according to (for example, a comparison table) (steps S5 and S6). The signal processing determination device 15 can be configured by a microcomputer or the like.

The principle of the rotation direction judgment of the present invention is as follows. When the rotating body 10 rotates in the direction of the arrow P in FIG. 1, the Hall elements 13a, 13c, and 13b are magnetically coupled to the detection member 11 in order, and the Hall elements 13a, 13c, and 13b (1a) (1) in FIG.
Signals A, C and B having waveforms as shown in b) are generated. The waveform (1a) shows two Hall elements A arranged outside,
The output when B is arranged so as to have a phase difference of 180 degrees, and the waveform (1b) is an output when arranged so as to have a phase difference of 90 degrees. As is apparent, since each detection member 11 passes through the Hall elements 13a, 13c, 13b in this order, the waveform C is generated next to the waveform A, and the waveform B is generated finally. Therefore, the difference signal (A-B) obtained by the difference calculation unit 15A has waveforms (2a) (2
It becomes like b). Looking at the level of the signal C at the time t1 when the sign of the difference signal (AB) changes from positive to negative,
It can be seen that the level is high in both cases.

On the other hand, if the direction of rotation of the rotating body 10 is reversed and becomes as indicated by the dotted arrow Q, each detecting member 1
1 is each Hall element, 13b, 13c
It is obvious that the output generation state is the state in which the waveforms A and B are interchanged in (1a) and (1b) of FIG. Therefore, the difference signal (A-B) in this case is the waveform (3a) (3b) of FIG.
become that way. Looking at the level of the signal C at the time when the sign of the difference signal (A-B) changes from positive to negative, it can be seen that the level is low in both cases, contrary to the above case.

From the above consideration, if the level of the signal C at the time t2 at which the sign of the difference signal (A-B) changes from positive to negative, the level is high (positive), the rotation direction is the P direction of ACB, and the opposite direction. It can be seen that the low level (negative) makes it possible to determine that the direction is the BCA Q direction.

As can be easily recognized from consideration of each waveform in FIG. 3, the level of the signal C at the time when the sign of the difference signal (A-B) changes from negative to positive is A in the rotation direction.
If it is in the P direction of CB, it is a low level (negative), and conversely B
In the Q direction of CA, the level is high (positive). Therefore, it is apparent that the rotation direction can be detected also by the level determination of the signal C at the time when the sign of the difference signal (A-B) changes from negative to positive. Furthermore, it goes without saying that the difference signal may be (BA) instead of (AB).

FIG. 4 is a block diagram when the signal judgment processing device 15 is constituted by an individual logic element or the like. Comparator 2
0 receives the signals A and B of the Hall elements 13a and 13b and outputs the waveforms as shown in (2a) and (2b) of FIG. The differentiating circuit 21 detects the falling edge of the output waveform and triggers the mono-multi 22 to generate a pulse having a predetermined width. Second
The comparator 23 compares the output signal of the hall element 13c with a reference value (for example, zero level), and generates a high level signal when the output C of the hall element 13c is equal to or more than the reference value.
The rotation direction determination circuit 25 is a first AND circuit 25B having two inputs of the outputs of the monomulti 22 and the second comparator 23.
And a second AND circuit 25C having two inputs, the output of the inverter 25 that inverts the output of the monomulti 22 and the output of the second comparator 23.

With the configuration shown in FIG. 4, it is possible to detect the same rotation direction as described above, and the AND circuit 25B produces an output indicating the P direction rotation and the AND circuit 25C produces an output indicating the Q direction rotation. it is obvious. Further, it will be easily understood that the (BA) signal can be used instead of the above, and the determination can be performed at the falling time of the difference signal.

[0014]

According to the present invention, it is not necessary to have a specific relationship between the arrangement intervals of the two detection elements located at both ends and the arrangement intervals of the detection members in order to detect the rotation direction. For example, even if the pitch of the gear changes, there is an advantage that the detection device having the same size and structure can be shared, which is also effective in cost reduction. In addition, two detection elements at both ends,
It is also possible to arrange so that the respective outputs have a phase difference of 180 degrees, so when detecting rotational speed, etc.
It is possible to increase the output of the difference signal to facilitate the speed detection and to accurately detect the rotation direction.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration and function of one embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment.

FIG. 3 is a waveform diagram of an output signal of each detection element in the example.

FIG. 4 is a block diagram of another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Rotating body 11 ... Detection member 13a-c ... Hall element 15 ... Signal processing determination device 15A ... Difference calculation part 1
5B ... Sign inversion detection section 15C ... Level determination section 15D ... Rotation direction determination section 20, 23 ... Comparator 21 ...
Differentiation circuit 22 ... Mono-multi circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References: Kaihei 5-59239 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01P 13/04

Claims (2)

(57) [Claims] 1. A first detection device and a second detection device which are arranged so as to be magnetically coupled with a detection member provided on the surface of a rotating body to be measured along a rotational locus and sequentially in time. An element and a third element arranged between the two detection elements
Detecting element, a difference calculating means for calculating a difference between outputs of the first and second detecting elements, a sign inversion detecting means for detecting that the sign of the difference is inverted and generating a timing signal, the timing Rotation direction determination that compares the output level of the third detection element at the time of signal generation with a reference value, and generates a signal indicating the rotation direction of the rotating body to be measured according to a predetermined reference according to the comparison result. And a rotation direction detecting device. 2. First and second detections arranged along the rotation locus of a detection member provided on the surface of the rotating body to be measured and so as to be magnetically coupled thereto sequentially in time. An element and a third element arranged between the two detection elements
Detection element, a first comparator having two inputs of the outputs of the first and second detection elements, differentiating means for differentiating the output of the first comparator, and mono-multi which is triggered by the output of the differentiating means. A second direction comparator that compares the output of the third detection element with a reference value, and a logical product circuit that receives the output of the monomulti and the output of the second comparator as input .