JP2001235483A - Rotation sensor unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation sensor unit whose reliability can be enhanced, in which the number of components can be reduced and whose costs can be reduced by a method wherein any toublesome operation and any troublesome adjustment are not required and the duty ratio of a square-wave spignal can be set automatically to an always ideal state. SOLUTION: The rotation sensor unit is provided with a rotation sensor 4 which outputs a pair of sine-wave voltage signals Va1, Va2 (and Nb1, Vb2) whose phases become opposite to each other according to the rotation of a motor 1. The unit is provided with reference-voltage circuits 31 (and 41) which output a reference voltage Vs at a level corresponding to the middle-point potential of both voltage signals. The unit is provided with square-wave generation circuits 32 (and 42) which synthesize both voltage signals and which generate square-wave signals Pa (and Pb) in a shape in which voltages of their synthesized signals Va (and Vb) are sliced by the reference voltage Vs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation sensor unit for detecting rotation of an object to be detected, such as a motor.

[0002]

2. Description of the Related Art For example, in a device for positioning a robot arm or the like by a servomotor, the position of an object to be positioned is detected by detecting the number of rotations of the motor, and a rotation sensor unit is used for the detection. You. One example is shown in FIGS.

[0003] A motor 1 has a shaft 2 for transmitting rotational power to a positioning object. A metal disk 3 is attached to a shaft 2 of the motor 1, and a rotation sensor 4 is disposed near the disk 3.

[0004] The rotation sensor 4 has a sensor circuit 11 and a sensor circuit 21. The sensor circuit 11 is a circuit in which four magnetoresistive elements whose resistance values change in accordance with a change in magnetism based on the rotation of the disk 3 are connected in a bridge circuit, and the bridge circuit is connected in accordance with the rotation of the disk 3 to be detected. When the resistance value balance changes, a pair of sinusoidal voltage signals Va1 and Va2 having phases opposite to each other are output.

The sensor circuit 21 changes the resistance balance of the bridge circuit according to the rotation of the disk 3,
A pair of sinusoidal voltage signals Vb1 and Vb2 having opposite phases to each other and having a predetermined phase difference, for example, 90 degrees with respect to voltage signals Va1 and Va2 output from first circuit 11.
Is output.

FIG. 10 shows the signal waveform of each part. The voltage signals Va1 and Va2 output from the sensor circuit 11 are supplied to the synthesis circuit 12. The synthesizing circuit 12 is a so-called waveform amplifying circuit, which synthesizes and amplifies the voltage signals Va1 and Va2 output from the sensor circuit 11, and
a is output. By the waveform synthesis here, the voltage signal Va
The noise (noise generated by the rotation of the motor 1, etc.) superimposed on Va1 and Va2 cancels each other and is removed.
A synthesized signal Va without noise can be obtained.

[0007] The composite signal Va is supplied to a square wave generating circuit 13. The square wave generation circuit 13 is a so-called voltage comparison circuit, and compares the synthesized signal Va with a reference voltage Vs based on the operation of the variable resistor 14 to slice the voltage of the synthesized signal Va by the reference voltage Vs. Square wave signal Pa
Generate

The voltage signal V output from the sensor circuit 21
b1 and Vb2 are supplied to the synthesis circuit 22. Synthesis circuit 2
Reference numeral 2 denotes a so-called waveform amplifying circuit that combines and amplifies the voltage signals Vb1 and Vb2 output from the sensor circuit 21, and outputs a combined signal Vb. By the waveform synthesis here, noise superimposed on the voltage signals Vb1 and Vb2 (noise generated by the rotation of the motor 1 and the like) is canceled out by each other, and the synthesized signal Vb without noise can be obtained.

The composite signal Vb is supplied to a square wave generating circuit 23. The square wave generation circuit 23 is a so-called voltage comparison circuit, which compares the composite signal Vb with a reference voltage Vs based on the operation of the variable resistor 24, thereby slicing the voltage of the composite signal Vb with the reference voltage Vs. Square wave signal Pb
Generate

The square wave signals Pa,
When one of Pb is counted by the subsequent control unit, the number of rotations of the motor 1 is captured, and the moving position of the positioning target is detected. Also, the square wave signal P
The direction of the phase shift between a and Pb is determined by the control unit at the subsequent stage, whereby the rotational direction of the motor 1 is captured, and the moving direction of the positioning target is detected.

When the level of the reference voltage Vs is changed by operating the variable resistors 14 and 24, the square wave signals Pa and P
The duty ratio of b (the ratio of the ON period within one cycle) changes. In order to ensure good controllability with respect to the detection of the rotation direction in the control unit at the subsequent stage, the duty ratio is set to 50.
Ideally it should be set to%.

[0012]

However, due to the influence of environmental temperature change and the like, the reference voltage Vs shown in FIG.
May fluctuate to the state indicated by the chain line, in which case the duty ratio cannot be maintained at 50%. For this reason, adjustment work by operating the variable resistors 14 and 24 is frequently required.

The present invention has been made in view of the above circumstances.
The purpose is to always automatically set the duty ratio of the square wave signal to the ideal state without any troublesome operation or adjustment, thereby improving reliability and reducing the number of parts. It is an object of the present invention to provide a rotation sensor unit capable of reducing the cost and reducing the cost.

[0014]

According to a first aspect of the present invention, there is provided a rotation sensor unit for outputting a pair of sinusoidal voltage signals having phases opposite to each other in accordance with the rotation of a detection object; A reference voltage circuit that outputs a reference voltage having a level corresponding to the midpoint potential of the signal; and a square wave generation circuit that combines the two voltage signals and generates a square wave signal in which the combined signal is shaped by the reference voltage. And.

According to a second aspect of the present invention, there is provided a rotation sensor unit for outputting a square wave signal in accordance with the rotation of an object to be detected. The pulse width to output the square wave signal as it is, and to generate and output a new square wave signal having the pulse width of the specified value or the vicinity when the pulse width of the square wave signal is out of the specified value or its vicinity. Control means.

[0016]

[1] Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In the drawings, the same parts as those in FIGS. 8 and 9 are denoted by the same reference numerals.
Detailed description is omitted.

As shown in FIG. 1, voltage signals Va1 and Va2 output from the sensor circuit 11 of the rotation sensor 4 are supplied to a reference voltage circuit 31 and a square wave generation circuit 32.

The reference voltage circuit 31 connects a series circuit of resistors 15 and 16 having the same resistance value between a signal input line of the voltage signal Va1 and a signal input line of the voltage signal Va2. Gain "1" at 16 interconnection points
The voltage followers 17 are connected to each other, and the midpoint potential of the voltage signals Va1 and Va2 is detected through the interconnection point of the resistors 15 and 16, and the reference voltage Vs of the level corresponding to the detected midpoint potential is detected. The output is provided via the voltage follower 17. This output is supplied to the square wave generation circuit 32.

The square wave generating circuit 32 generates voltage signals Va1,
Va2 is synthesized, and the voltage of the synthesized signal Va is set to the reference voltage V
This is a waveform amplifying circuit configured to amplify around the level of s, and generates a square wave signal Pa having a shape obtained by shaping (slicing) the waveform of the synthesized signal Va based on the reference voltage Vs. Note that the voltage signal V1 is obtained by combining the voltage signals Va1 and Va2.
Noise superimposed on a1 and Va2 (noise caused by the rotation of the motor 1 and the like) is canceled by each other and removed, so that a synthesized signal Va without noise can be obtained.

On the other hand, the voltage signals Vb 1 and Vb 2 output from the sensor circuit 21 of the rotation sensor 4 are
And supplied to the square wave generation circuit 42.

The reference voltage circuit 41 connects a series circuit of resistors 25 and 26 having the same resistance value between the signal input line of the voltage signal Vb1 and the signal input line of the voltage signal Vb2. Gain "1" at 26 interconnects
The voltage followers 27 are connected to each other, and a midpoint potential of the voltage signals Vb1 and Vb2 is detected via an interconnection point of the resistors 25 and 26, and a reference voltage Vs of a level corresponding to the detected midpoint potential is detected. The output is made via the voltage follower 27. This output is supplied to the square wave generation circuit 42.

The square wave generating circuit 42 generates the voltage signals Vb1,
Vb2 is a waveform amplifying circuit configured to combine Vb2 and amplify the combined signal Vb around the level of the reference voltage Vs.
A square wave signal Pb is generated by shaping (slicing) the voltage of the synthesized signal Vb based on the reference voltage Vs. The voltage signal Vb1 and Vb2 are combined to form the voltage signal Vb.
Noise superimposed on b1 and Vb2 (noise caused by rotation of the motor 1 and the like) is canceled out by each other and removed, and a synthesized signal Vb without noise is obtained.

With such a configuration, the composite signal Va, the reference voltage Vs, and the square wave signal Pa having the waveforms shown in FIG.
The composite signal Vb, the reference voltage Vs, and the square wave signal Pb can be obtained.

That is, even when the amplitude of the synthesized signal Va fluctuates due to the influence of environmental temperature change or the like, the level of the reference voltage Vs follows the fluctuation, and the amplitude of the synthesized signal Va is always 1%.
The level of the reference voltage Vs corresponds to the position of / 2. Thereby, the duty ratio of the square wave signal Pa is always the ideal 5
0%.

Similarly, even when the amplitude of the composite signal Vb fluctuates due to the influence of environmental temperature change or the like, the level of the reference voltage Vs follows the fluctuation, and the level of the amplitude of the composite signal Vb is always 1 /.
The level of the reference voltage Vs corresponds to the position 2. Thereby, the duty ratio of the square wave signal Pb is always 50
%.

When one of these square wave signals Pa and Pb is counted by the control unit at the subsequent stage, the rotation speed of the motor 1 is captured, and the moving position of the positioning object is detected. Further, the direction of the phase shift of the square wave signals Pa and Pb is determined by the subsequent control unit, so that the rotation direction of the motor 1 is captured, and the moving direction of the positioning target is detected.

As described above, the duty ratio of the square wave signals Pa and Pb is always automatically set to the ideal 50%, so that the phase difference between the square wave signals Pa and Pb is always maintained at the optimum 90 degrees. Can be. Therefore, high reliability regarding rotation detection can be ensured, for example, it is possible to accurately and accurately detect the rotation direction in the subsequent control unit.

In addition, since troublesome operations and adjustments using a conventional variable resistor are not required at all, the burden on personnel and the like can be reduced, and the number of components such as the variable resistor and its peripheral circuits can be reduced. Can be reduced,
Cost reduction can be achieved. Regarding this reduction in the number of parts,
The greater the number of phases of the rotation sensor 4 (the number of sensor circuits), the more remarkable effects can be obtained.

[2] A second embodiment will be described.
In the drawings, the same parts as those in FIGS. 8 and 9 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 3, a pulse width control means is connected to the output terminal of the square wave generating circuit 13. If the pulse width of the square wave signal Pa output from the square wave generation circuit 13 is a specified value (or in the vicinity thereof), the pulse width control means outputs the same square wave signal Pa as it is, and outputs the square wave signal Va.
If the pulse width deviates from the specified value (or its vicinity), a new square wave signal having the same appropriate pulse width as the specified value (or its vicinity) is generated and output.
It comprises a first pulse width controller 18 and a second pulse width controller 19.

That is, the pulse width control unit 18 compares the pulse width of the square wave signal Pa with a specified value (or its vicinity), and if the pulse width of the square wave signal Pa is a specified value (or its vicinity). Also, when the pulse width of the square wave signal Pa is smaller than a specified value (or in the vicinity thereof), the square wave signal Pa is output as it is as an inverted square wave signal Qa, and the pulse width of the square wave signal Pa is changed. Is larger than the specified value (or its vicinity), a new square wave signal Qa having the same pulse width D as the specified value (or its vicinity) is generated based on the falling edge of the square wave signal Pa. Output. This output is supplied to the pulse width control unit 19.

The pulse width control unit 19 includes the pulse width control unit 1
The pulse width of the square wave signal Qa supplied from 8 is compared with a specified value (or its vicinity). If the pulse width of the square wave signal Qa is a specified value (or its vicinity), the square wave signal Qa is The inverted square wave signal Ra is output as it is as it is, and when the pulse width of the square wave signal Qa is larger than a specified value (or in the vicinity thereof), that is, the pulse width of the original square wave signal Pa is specified value (or If it is smaller than (near), a new square wave signal Ra having the same pulse width D as the specified value (or its vicinity) is generated and output with reference to the falling edge of the square wave signal Qa.

Further, pulse width control means is connected to the output terminal of the square wave generation circuit 23. This pulse width control means generates a square wave signal Vb output from the square wave generation circuit 23.
If the pulse width of the square wave signal Vb is a specified value (or in the vicinity thereof), the square wave signal Vb is output as it is, and the square wave signal Vb is output.
If the pulse width of b is outside the specified value (or its vicinity), a new square wave signal having the same appropriate pulse width as the specified value (or its vicinity) is generated and output. , And a second pulse width control unit 29.

That is, the pulse width control unit 28 compares the pulse width of the square wave signal Pb with a specified value (or its vicinity), and if the pulse width of the square wave signal Pb is a specified value (or its vicinity). Also, when the pulse width of the square wave signal Pb is smaller than a specified value (or in the vicinity thereof), the same square wave signal Pb is output as the inverted square wave signal Qb as it is, and the pulse width of the square wave signal Pb is changed. Is larger than the specified value (or its vicinity), a new square wave signal Qb having the same pulse width D as the specified value (or its vicinity) is generated based on the falling edge of the square wave signal Pb. Output. This output is supplied to the pulse width control unit 29.

The pulse width control unit 29 includes the pulse width control unit 2
The pulse width of the square wave signal Qb from FIG. 8 is compared with a specified value (or its vicinity). If the pulse width of the square wave signal Qb is a specified value (or its vicinity), the square wave signal Qb is inverted as it is. Is output as a square wave signal Rb in a state where the square wave signal Qb has a pulse width larger than a specified value (or in the vicinity thereof).
If the pulse width of b is smaller than the specified value (or its vicinity), a new square wave signal Rb having the same pulse width D as the specified value (or its vicinity) is based on the falling edge of the square wave signal Qb. Is generated and output.

The specified values defined in the pulse width control units 18, 19, 28 and 29 correspond to the original pulse widths of the square wave signals Pa and Pb. Further, the pulse width control units 18, 1
Each of 9, 28, and 29 is constituted by an IC circuit having a timer function with a variable time constant.

Next, the operation of the above configuration will be described. In order to ensure good controllability with respect to rotation direction detection in the control unit at the subsequent stage, the phase difference between the square wave signals Pa and Pb is determined by using FIG.
It is important to always maintain the optimum value, for example, 90 degrees, as shown in FIG. 5, but the square wave signals Pa and Pb may be generated due to the case where the motor 1 is driven at high speed, the influence of environmental temperature change, or the superposition of noise. May be wider than the original value (shown by broken lines) as shown in FIG. 5, or may be narrower than the original value (shown by broken lines) as shown in FIG.

In this case, it is impossible to maintain the phase difference between the square wave signals Pa and Pb at an optimum value. The phase difference may be lost (phase difference is 0 degree).

When the pulse widths of the square wave signals Pa and Pb are larger than a specified value as shown in FIG.
In steps 8 and 28, square wave signals Qa and Qb having the same appropriate pulse width D as the specified value are generated, and are output as square wave signals Ra and Rb through the pulse width control units 19 and 29. .

As shown in FIG. 6, when the pulse widths of the square wave signals Pa and Pb are smaller than a specified value, the square wave signals P
a and Pb pass through the pulse width controllers 18 and 28 and flow into the pulse width controllers 19 and 29 as square wave signals Qa and Qb, and the pulse width controllers 19 and 29 have the same appropriate pulse width as the specified value. Square wave signals Ra and Rb having D are generated and output.

Therefore, even when the motor 1 is driven at a high speed, or when the ambient temperature changes or noise is superimposed, the square wave signals Ra and Rb having appropriate pulse widths and phase differences always appear. Can be obtained.

When either one of the square wave signals Ra and Rb is counted by the control unit at the subsequent stage, the motor 1
Is detected, and the moving position of the positioning target is detected. Further, the direction of the phase shift of the square wave signals Ra and Rb is determined by the control unit at the subsequent stage, so that the rotation direction of the motor 1 is captured, and the moving direction of the positioning object relative to the positioning object is detected.

As an application of the second embodiment,
The rotation sensor unit can be used as a rotation speed limiter for the motor 1.

For example, the upper limit rotation speed of the motor 1 is 3
000 rotations are determined, the square wave signals Pa and P obtained when the motor 1 operates at the 3000 rotations
The pulse width control unit 18, 1 uses the pulse width of b as a specified value.
9, 28 and 29 are set. When the motor 1 runs away due to an abnormality of the motor 1 or a malfunction of a peripheral device, and its rotation speed exceeds the upper limit rotation speed and rises to 3500 rotations, the pulse widths of the square wave signals Pa and Pb become smaller than a specified value.

However, the pulse width control units 19 and 29
Output square wave signals Ra and Rb having the same appropriate pulse width D as the specified value. By feeding back the square wave signals Ra and Rb to the drive control system of the motor 1, the rotation speed of the motor 1 can be suppressed to the upper limit rotation speed of 3000.

[3] A third embodiment will be described.
The third embodiment has a configuration in which the first embodiment and the second embodiment are combined. That is, as shown in FIG. 7, the square wave generation circuit 31 in the first embodiment
The square wave signal Ra generated in the second embodiment is input to the pulse width control unit 18 in the second embodiment, and the square wave signal Rb generated in the square wave generation circuit 41 in the first embodiment is changed in the second embodiment. Input to the pulse width control unit 28 in the embodiment. According to such a configuration, the operation and effect described in the first embodiment can be obtained, and the operation and effect described in the second embodiment can be obtained. The present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention.

[0047]

As described above, according to the present invention, the duty ratio of a square wave signal can always be automatically set to an ideal state without any troublesome operation or adjustment. It is possible to provide a rotation sensor unit that can improve the performance and can reduce the number of parts and cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment.

FIG. 2 is a diagram showing signal waveforms of respective units according to the first embodiment.

FIG. 3 is a diagram showing a configuration of a second embodiment.

FIG. 4 is a diagram showing a waveform of a square wave signal having an appropriate phase difference in the second embodiment.

FIG. 5 is a diagram illustrating signal waveforms of respective units when a pulse width is expanded in the second embodiment.

FIG. 6 is a diagram illustrating signal waveforms of respective units when a pulse width is reduced in the second embodiment.

FIG. 7 is a diagram showing a configuration of a third embodiment.

FIG. 8 is a diagram showing a configuration of each embodiment and a conventional motor and its peripheral portion.

FIG. 9 is a diagram showing a configuration of a conventional rotation sensor unit.

FIG. 10 is a diagram showing signal waveforms at various parts in a conventional rotation sensor unit.

FIG. 11 is a diagram showing an example of a change in the duty ratio of a square wave signal in a conventional rotation sensor unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Motor, 3 ... Disk, 4 ... Rotation sensor, 11 ... Sensor circuit, 21 ... Sensor circuit, 31 ... Reference voltage circuit, 41 ...
Reference voltage circuit, 32: square wave generation circuit, 42: square wave generation circuit, 18: pulse width control unit, 19: pulse width control unit, 28: pulse width control unit, 29: pulse width control unit

Claims (2)

[Claims] 1. A rotation sensor for outputting a pair of sinusoidal voltage signals having phases opposite to each other in accordance with the rotation of a detection target, and a reference for outputting a reference voltage having a level corresponding to a midpoint potential of the two voltage signals. A rotation sensor unit, comprising: a voltage circuit; and a square wave generation circuit that combines the two voltage signals and generates a square wave signal in which the combined signal is shaped based on the reference voltage. 2. A rotation sensor unit for outputting a square wave signal in accordance with the rotation of an object to be detected, wherein if the pulse width of the square wave signal is at or near a specified value, the square wave signal is output as it is. Pulse width control means for generating and outputting a new square wave signal having a pulse width of a specified value or a vicinity thereof when the pulse width of the square wave signal deviates from a specified value or a vicinity thereof. Characteristic rotation sensor unit.