JP2611082B2 - Rotation detection device - 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 detecting device, and more particularly, to a rotation detecting device which has a frequency corresponding to a rotation speed of a rotating body of approximately 90 degrees.
And a pair of pulse signals having a phase difference of
The present invention relates to a rotation detecting device configured to determine a rotation direction of a rotating body based on the pair of pulse signals.

[0002]

2. Description of the Related Art Conventionally, as this type of apparatus, an apparatus having a configuration as shown in FIG. 9 has been generally used. In FIG. 1, a rotating body 1 made of a soft magnetic material is formed with gear teeth 1a having a predetermined pitch around the rotating body 1, and is separated from the rotating body 1 by a half of the gear pitch in the rotating direction. Two Hall elements 2a and 2b are arranged so as to face gear teeth. Further, the Hall elements 2a and 2b are
The permanent magnet 3 is disposed so as to be opposed to the peripheral surface of the rotating body 1.

[0003] With this configuration, the distance between the permanent magnet 3 and the peripheral surface of the rotating body 1 changes due to the rotation of the rotating body 1, and the amount of magnetic flux acting on the Hall elements 2a and 2b changes. As a result, each of the Hall elements 2a and 2b generates an electric signal which changes in a pseudo sine wave shape having a phase difference of about 90 ° from each other, and passes this electric signal through the waveform shaping circuits 4a and 4b to thereby generate pulse signals having a phase difference of about 90 ° Is obtained. This pulse signal is input to a rotation direction determination circuit 5 to determine the rotation direction, and the gate 6a, 6b is opened / closed by the output of the determination circuit 5 to select and output one of the pulse signals. I have.

[0004]

In the conventional apparatus described above, the phase difference between the two pulse signals used to determine the rotation direction is determined by the distance between the two Hall elements 2a and 2b, the gear pitch of the rotating body 1, and the like. When used in combination with the rotating body 1 having a greatly different gear pitch, there is a problem that the two phase differences greatly deviate from 90 °.

A case (not shown) for accommodating the hall elements 2a and 2b is provided in a relation that the interval between the two hall elements 2a and 2b is set to one half of the gear pitch of the rotator 1. As the pitch of the pitch 1 increases, the pitch increases, and there is a problem in that there is a limit to miniaturization.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and provides a rotation detecting device suitable for miniaturization capable of generating two pulse signals having phases substantially 90 ° different from each other regardless of the gear pitch of a rotating body. It is intended to be.

[0007]

To achieve the above object, a rotation detecting apparatus according to the present invention comprises a pair of pulse signals having a frequency corresponding to the rotation speed of a rotating body and having a phase difference of about 90 ° from each other. In the rotation detecting device, which is generated and determines the rotation direction of the rotating body based on the pair of pulse signals, the rotation detecting device includes a gear that is separated from the rotating direction of the rotating body made of a soft magnetic material having gear teeth formed therearound. Two Hall elements arranged so as to face the teeth of the rotor, a permanent magnet arranged so as to face the peripheral surface of the rotating body with the Hall element sandwiched between the rotating body, and A first comparator having a signal output of the same polarity connected to + and-inputs, and a second comparator having one signal output of the Hall element and a reference voltage point of the Hall element connected to + and-inputs With It is characterized in that to obtain a pulse signal having a phase difference of approximately 90 ° to the output of the first and second comparators.

In order to achieve the above object, a rotation detecting device according to the present invention generates a pair of pulse signals having a phase difference of about 90 ° from each other at a frequency corresponding to the rotation speed of a rotating body. In the rotation detecting device, the rotation direction of the rotating body is determined based on the pulse signal of the rotating body, and the rotating direction of the rotating body made of a soft magnetic material having gear teeth formed around the rotating body is opposed to the gear teeth. , Three permanent magnets arranged so as to face the peripheral surface of the rotating body with the Hall element sandwiched between the rotating body, and the same polarity of the elements on both sides of the hall element. A first comparator whose signal output is connected to the + and-inputs;
A second comparator having a signal output of a central element of the Hall element and a reference voltage point of the element connected to + and-inputs, and having an output of the first and second comparators of about 90 °; A pulse signal having a phase difference is obtained.

[0009]

According to the above construction, the first comparator is provided in the rotation direction of the rotating body made of a soft magnetic material having gear teeth formed therearound, and the first comparator is arranged so as to face the gear teeth. Since the signal outputs of the same polarity of the Hall elements are compared, a pulse signal that is inverted near the peak-to-peak point of the output of both Hall elements is generated. Since the second comparator compares one signal output of the Hall element with its reference voltage point, it generates a pulse signal that is inverted at the reference voltage point. Therefore, the pulse signals generated by the first and second comparators have a phase difference of about 90 ° regardless of the position of the Hall element with respect to the gear teeth.

Further, according to the above configuration, the first comparator is arranged in the direction of rotation of the rotating body made of a soft magnetic material having gear teeth formed around the first comparator and opposed to the gear teeth. Since the signal outputs of the same polarity of the elements on both sides of the two Hall elements are compared, a pulse signal that is inverted near the peak / peak point of the output of both Hall elements is generated. Since the second comparator compares the signal output of the central Hall element with the reference voltage point, it generates a pulse signal that is inverted at the reference voltage point. Therefore, the pulse signals generated by the first and second comparators have a phase difference closer to 90 ° than in the above case regardless of the position of the Hall element with respect to the gear teeth.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing an embodiment of a rotation detecting device according to the present invention. In FIG. 1, reference numerals 11a and 11b denote Hall elements, and these two Hall elements 11a and 11b are provided around a soft magnetic material. In the rotating direction of the rotating body (not shown) on which the gear teeth of the pitch are formed, the gear teeth are arranged close to each other regardless of the gear pitch and are arranged so as to face the gear teeth. Further, a permanent magnet (not shown) is arranged so as to face the peripheral surface of the rotating body with the Hall elements 11a and 11b interposed therebetween.

The Hall elements 11a and 11b have their power input connected in series between the power supply _Vcc and the ground, and the + side signal output of the Hall elements 11a is supplied to the comparators 12a and 12b.
b, the + side signal output of the Hall element 11b is connected to the-input of the comparator 12a, and the Hall element 11b
The negative signal outputs of a and 11b are interconnected and connected to the negative input of the comparator 12b.

The outputs of the comparators 12a and 12b are connected to a rotation direction judging circuit 13 and are connected to AND gates 14a and 14b which are opened and closed by the output of the rotation direction judging circuit 13. AND gate 14
A pulse signal is obtained at one of the outputs of the a and b according to the rotation direction of the rotating body.
The pulse signal output to b is synthesized by the OR gate 15 and output.

In the above configuration, when a rotating body having gear teeth (not shown) around it rotates, the Hall elements 11a,
As shown by a solid line and a dotted line in FIG. 2A, a pseudo sine wave signal fluctuating around V _CC / 2 is obtained at the + side output of 11b, and this signal is applied to the + and-inputs. The output of the comparator 12a, which is input to each of them, is shown in FIG.
As shown in (b), a pulse signal that is at the H level during a period when the output of the Hall element 11a is larger is obtained. Further, the output of the Hall element 11a is changed to the + input, and the Hall element 11a,
As shown in FIG. 2 (c), the output of the comparator 12b, whose interconnection point of 11b is input to the-input, includes a pulse signal which becomes H level while the output of the Hall element 11a is larger than V _CC / 2 as shown in FIG. can get.

As can be seen from FIG.
The pulse signals obtained at the outputs of a and 12b have a phase difference obtained by subtracting an angle of half of the arrangement phase difference of the Hall elements 11a and 11b from 90 °, and the distance between the Hall elements 11a and 11b is short. As a result, the phase difference becomes closer to 90 °.

As the rotation direction judging circuit 13 for judging the rotation direction based on the pulse signals having different phases, for example, a circuit as shown in FIG. 3 can be employed. Rotation direction determination circuit 1
Reference numeral 3 includes NAND gates 13a to 13c and a D-type flip-flop 13d. NAND gate 13a
And 13b constitute an RS flip-flop. When the two inputs are different or both are at H level, they output signals of different levels, but both inputs are at L level.
At the time of the level, the H level is output from each. These outputs are input to the NAND gate 13c, and the NAND gate 13c outputs the L level only when each input is at the H level. The output of the NAND gate 13c becomes the clock input C of the D-type flip-flop 13d. The D-type flip-flop 13d latches the D input at the positive edge of the clock input C and outputs it to the Q terminal. Output.

Next, the operation will be described. FIG. 4 is a waveform diagram showing signals at respective points when the rotating body is rotating in one direction. The pulse signal from the comparator 12a is advanced by approximately 90 ° from the pulse signal from the comparator 12b, and the pulse from the comparator 12a. Since the pulse signal from the comparator 12b changes to the L level approximately 1/4 cycle after the signal changes to the L level, the NAND gates 13a and 13b
Output an H level signal, and the output of the NAND gate 13c turns to L level.

Thereafter, when a further 1/4 cycle has elapsed, the pulse signal from the comparator 12a changes to H level, so that the output of the NAND gate 13a changes to L level and the output of the NAND gate 13c changes to H level. As a result, the D-type flip-flop 13d is triggered, and the pulse signal from the comparator 12a which is at the H level is latched.
4a is opened, and the pulse signal from the comparator 12a is output from the OR gate 15 as a rotation detection pulse signal.

FIG. 5 shows a signal at each point when the rotating body is rotating in the opposite direction. The pulse signal from the comparator 12b is substantially 9 times smaller than the pulse signal from the comparator 12a.
0 °, the pulse signal from the comparator 12b changes to the L level, and after approximately 1/4 cycle, the comparator 12a
Changes to the L level, the NAND gates 13a and 13b both output H level signals, and the output of the NAND gate 13c changes to the L level.

Thereafter, when a further 1/4 cycle has elapsed, the pulse signal from the comparator 12b changes to H level, so that the output of the NAND gate 13a changes to L level and the output of the NAND gate 13c changes to H level. This triggers the D-type flip-flop 13d to latch the pulse signal from the comparator 12a at L level, so that the Q terminal goes to L level and the inverted Q terminal goes to H level to open the AND gate 14b. The OR gate 15 outputs the pulse signal from the comparator 12b as a rotation detection pulse signal.

FIG. 6 shows another embodiment, and the same parts as those of the embodiment described above with reference to FIG. 1 are denoted by the same reference numerals. In this embodiment, a third Hall element 11c is provided between two Hall elements 11a and 11b which are close to each other and are spaced apart in the rotation direction of the rotating body, and a signal on the + side of the Hall element 11c is provided. output to the positive input of the comparator 12b, are divided voltage is applied by the same resistance R ₁ and the variable resistor R ₂ - side signal output of the comparator 11c - are connected to the input.

In the above configuration, when the rotating body having gear teeth (not shown) around it rotates, the Hall elements 11a,
The solid lines in FIG. 7 (a) indicate the + side outputs of 11c and 11b.
Pseudo-sinusoidal signals fluctuating around V _cc / 2 are obtained as indicated by the dashed line and the dotted line, respectively, and these signals are input to the + and-inputs, respectively.
As shown in FIG. 7 (b), the output of
A pulse signal which is at the H level during a period when the output of a is larger is obtained. This pulse signal is the same as that shown in FIG.

Further, the output + input of the Hall element 11c, a voltage of V _CC / 2 is - the output of the comparator 12b is inputted to the input, the output of the Hall element 11c as shown in FIG. 7 (c) Is high when V _CC is higher than V _CC / 2. As can be seen from FIG. 7, the pulse signals obtained at the outputs of the comparators 12a and 12b have a phase difference of exactly 90 °.

FIG. 8 shows a configuration example of a rotation detecting sensor used in the above-described rotation detecting device. A permanent magnet 22 and a permanent magnet 22 are provided inside a case 21 made of a non-magnetic material.
A yoke 23 made of a ferromagnetic material provided on one side and a Hall IC 11 provided with a plurality of Hall elements provided on the other side are built in, and the Hall IC 11 is made of a soft magnetic material. The rotating body 1 having the gear teeth 1a is disposed so as to face the rotating body 1. In addition, 1b is a rotating shaft of the rotating body 1, 24 is a sensor mounting flange, 25 is a sealing mold for sealing the case 21 while maintaining water tightness, and 26 is a lead cord of the sensor.

In the figure, the Hall elements in the Hall IC are drawn sufficiently separated for easy understanding, but actually three Hall elements are arranged within a range of about 1 mm. I have. Also, the width D of the permanent magnet 22 is preferably approximated to the gear teeth 1a of the rotating body 1, that is, the width d of the convex portion of the rotating body 1, and is set so as to fall within the range of 0.5d <D <1.5d. (Here, the width D is set to about 3 mm), so that a sensor with sufficiently high detection accuracy can be obtained.

[0026]

As described above, according to the present invention, a pair of pulse signals obtained has a phase difference of about 90 ° regardless of the position of the Hall element with respect to the gear pitch of the rotating body. The size can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a rotation detecting device according to the present invention.

FIG. 2 is a waveform diagram showing a state of each unit in FIG.

FIG. 3 is a diagram showing a specific example of a rotation direction determining circuit in FIG. 1;

FIG. 4 is a waveform diagram showing states of respective parts for explaining the operation of the circuit of FIG. 3 when the rotating body rotates in one direction.

FIG. 5 is a waveform diagram showing states of respective parts for explaining the operation of the circuit of FIG. 3 when the rotating body rotates in another direction.

FIG. 6 is a diagram showing another embodiment of the rotation detecting device according to the present invention.

FIG. 7 is a waveform chart showing a state of each unit in FIG. 7;

FIG. 8 is a diagram showing a configuration example of a rotation detection sensor used in the apparatus shown in FIGS. 1 and 6;

FIG. 9 is a diagram illustrating an example of a conventional rotation detection device.

[Explanation of symbols]

 Reference Signs List 1 rotating body 1a gear teeth 11a, 11b, 11c Hall element 12a first comparator 12b second comparator 22 permanent magnet

Claims (2)

(57) [Claims] 1. A pair of pulse signals having a frequency according to the rotation speed of a rotating body and having a phase difference of about 90 ° are generated, and the rotation direction of the rotating body is determined based on the pair of pulse signals. In the rotation detecting device, two Hall elements are arranged in the rotation direction of a rotating body made of a soft magnetic material having gear teeth formed therearound and arranged so as to face the gear teeth. A permanent magnet arranged between the rotating body and facing the peripheral surface of the rotating body, a first comparator having the same polarity signal output of the Hall element connected to + and-inputs, A second comparator having one signal output of the Hall element and a reference voltage point of the Hall element connected to + and-inputs, and having a phase difference of about 90 ° between the outputs of the first and second comparators; Pulse signal with A rotation detecting device characterized by obtaining a signal. 2. A method according to claim 1, wherein a pair of pulse signals having a frequency corresponding to the rotation speed of the rotator and having a phase difference of about 90 ° are generated, and the rotation direction of the rotator is determined based on the pair of pulse signals. In the rotation detecting device, three Hall elements are arranged in the rotation direction of a rotating body made of a soft magnetic material having gear teeth formed therearound and arranged so as to face gear teeth; A first permanent magnet which is disposed between the rotating body and a peripheral surface of the rotating body so as to face the peripheral surface of the rotating body; and a signal output of the same polarity of elements on both sides of the Hall element is connected to + and-inputs. A comparator, and a second comparator in which a signal output of a central element of the Hall element and a reference voltage point of the element are connected to + and-inputs, and an output of the first and second comparators is substantially provided. Has a phase difference of 90 ° A rotation detection device characterized in that a pulse signal is obtained.