JPH044179Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic rotary encoder for detecting the rotation angle of a magnetic track formed on a rotating drum.

2. Description of the Related Art It is known that a plurality of magnetic resistance elements are used as a magnetic detection body of a magnetic rotary encoder for detecting the rotation angle of a magnetic track formed on a rotating drum. That is, as shown in FIG. 1, a magnetic detecting body 2 having a structure to be described later is arranged on the side surface of a rotating drum 1 on a disc in close proximity to a magnetic track 11 magnetized with a magnetic pitch length P. The magnetic detection body 2 is configured to convert the change in the magnetic field into an electric signal when the magnetic field is changed by the rotation of the rotary drum 1. The output (electrical signal) from this magnetic detector 2 is input to the signal processing circuit 3, and the signal processing circuit 3 generates pulse signals having mutually different phases, such as A phase output and B phase output, as shown in the figure. The rotation angle (position) of the magnetic track 11 is detected using this pulse signal.

However, in the conventional magnetic rotary encoder, in order to increase the number of pulses per rotation of the rotary drum 1, the magnetic pitch length P of the magnetic track 11 must be increased.
Although it is necessary to reduce the magnetic pitch length, it becomes difficult to form a magnetization pattern.
Furthermore, there are also problems in manufacturing the magnetic detector 2 and the gap between the magnetic track 11 and the magnetic detector 2. Further, it is difficult to substantially reduce the magnetic pitch length by increasing the size of the rotating drum 1 because the equipment in which the magnetic rotary encoder is housed is becoming smaller.

An object of the present invention is to provide a magnetic rotary encoder that can increase the number of pulses per rotation of the rotating drum without reducing the magnetic pitch length.

According to the present invention, first and second magnetic tracks are arranged near a magnetic track magnetized with a predetermined magnetization pitch length on a rotating drum at a predetermined interval with respect to the pitch length. A magnetic device comprising a magnetic detector, generating pulse signals having different phases based on the outputs of the first and second magnetic detectors, and detecting the rotation angle of the magnetic track based on the pulse signals. In the rotary encoder, the first
a first arithmetic unit for non-inverting amplifying the output of the magnetic detector to obtain a first detection signal; and a first computing unit for non-inverting amplifying the output of the first magnetic detector to obtain a second detection signal. a second arithmetic unit for non-inverting amplifying the output of the second magnetic detector to obtain a third detection signal; a fourth calculation unit for amplifying and obtaining a fourth detection signal; a first voltage comparator for obtaining a first comparison signal from the first and second detection signals; and a first voltage comparator for obtaining a first comparison signal from the first and second detection signals; a second voltage comparator for obtaining a second comparison signal from the fourth detection signal; and a third voltage comparator for obtaining a third comparison signal from the first and third detection signals. , a fourth voltage comparator for obtaining a fourth comparison signal according to the first and fourth detection signals; and a fourth voltage comparator for obtaining a first output signal according to the first and second comparison signals. a first exclusive OR circuit for obtaining a second output signal by means of the third and fourth comparison signals;
A magnetic rotary encoder characterized by having an OR circuit is obtained.

The present invention will be described below with reference to embodiments shown in the drawings.

First, a conventional magnetic rotary encoder will be explained with reference to FIGS. 2 to 4. The magnetic detecting body 2 shown in FIG. is P/4
Eight magnetoresistive elements 6a, 6b, with a spacing of
6c, 6d, 6e, 6f, 6g, and 6h are arranged, one end of the magnetoresistive element 6a, 6b, 6c, and 6d is connected to the positive side of the voltage source 6i (V _D ), and the other end is connected to the magnetoresistive element, respectively. 6g, 6h, 6
e, 6f, and further connected to the magnetoresistive element 6
g, 6h, 6e, and 6f are connected to the negative side of the voltage source 6i. However, essentially four series circuits are connected in parallel, and the magnetoresistive elements 6a, 6g, 6c, 6e are connected to the first magnetic detector 61, and the magnetoresistive elements 6d, 6f, 6b, 6h.
is the second magnetic detecting body 62, and as shown in the figure, between the magnetic resistance elements 6a and 6g, between 6c and 6e, and between 6d and 6
Between f and between 6b and 6h, terminals A, B, and
C and D are provided. Therefore, the output of terminal A and the output of terminal B are out of phase by P/2, the output of terminal C and the output of terminal D are also out of phase by P/2, and the output of terminal A is out of phase by P/2. The output and the output from terminal C will have a phase shift of P/4.

Terminals A, B, C, and D are connected to an arithmetic circuit as shown in FIG. As shown in the figure, this arithmetic circuit constitutes a high-input differential amplifier with an operational amplifier 8 connected to a terminal A, an operational amplifier 9 connected to a terminal B, an operational amplifier 10 connected to a terminal C,
The operational amplifier 11 connected to the terminal D constitutes a high input type differential amplifier. It is composed of a voltage comparator 12 which inputs the outputs of the operational amplifiers 8 and 9 and compares the voltages, and a voltage comparator 13 which inputs the outputs of the operational amplifiers 10 and 11 and compares the voltages. .

When the rotating drum (not shown, the magnetic track moves in the direction of the arrow in FIG. 2) rotates,
A voltage is induced in the angular magnetoresistive element, and since the magnetic pitch length is P, this voltage has a waveform with P as one period. As is clear from the above, the voltage V ₁ output from the operational amplifier 8 and the voltage V ₂ output from the operational amplifier 9 are out of phase by P/2. In other words, V ₂ is inverted. Therefore, the output V _A from the voltage comparator 12 has a pulse waveform with a period P as shown in FIG. Furthermore, the voltage V ₃ output from the operational amplifier 10 and the voltage V ₄ output from the operational amplifier 11 are out of phase by P/2, and furthermore, the phase between V ₁ and V ₄ is P/4.
Since the output from voltage comparator 13 is shifted by
V ₃ has a phase of P/4 compared to V _A as shown in Figure 4.
A pulse with a period of P is obtained.

However, this magnetic rotary encoder has various problems as mentioned above, such as the fact that the magnetic pitch length P must be reduced in order to increase the number of pulses.

Next, the magnetic rotary encoder according to the present invention will be explained with reference to FIGS. 5 to 7. The magnetic pitch length of the magnetic track is P, and the magnetic detector shown in FIG. 2 is used.

First, referring to FIG. 5, the terminal A of the first magnetic detector 61 is connected to the non-inverting terminal of the operational amplifier 8, and the terminal B is connected to the non-inverting terminal of the operational amplifier 9. The output sides of operational amplifiers 8 and 9 are connected via three resistors R ₁ , R ₂ , R ₃ , and
Feedback is provided to each inverting terminal.
Similarly, the terminal C of the second magnetic detector 62 is connected to the non-inverting terminal of the operational amplifier 10, and the terminal D is connected to the non-inverting terminal of the operational amplifier 11. The output side of operational amplifiers 10 and 11 has three resistors R ₁ ,
They are connected via R ₂ and R ₃ and fed back to their respective inverting terminals as shown.

Furthermore, as shown in the figure, the output V ₁ of the operational amplifier 8
The output V ₂ of the operational amplifier 9 and the output V 2 of the operational amplifier 9 are input to the voltage comparator 12 , and the output V ₃ of the operational amplifier 10 and the output V ₄ of the operational amplifier 11 are input to the voltage comparator 13 . Also, V ₁ and V ₃ are sent to the voltage comparator 13, and V ₁ and V 3 are sent to the voltage comparator 13.
V ₄ is input to voltage comparator 14 . Furthermore, the output V ₅ of the voltage comparator 12 and the output of the voltage comparator 13
V ₆ is input to the exclusive OR circuit 16 , and the output V ₇ of the voltage comparator 14 and the output V ₈ of the voltage comparator 15 are input to the exclusive OR circuit 17 .

Now, to explain the operation of the above-mentioned magnetic rotary encoder, as mentioned above, the outputs from the first magnetic detector 61 and the second magnetic detector 62 are the operational amplifiers 8 and 9 and the operational amplifier 1, respectively.
Input to 0,11 and output from each operational amplifier
V ₁ , V ₂ , V ₃ , and V ₄ have waveforms as shown in FIG. In other words, the waveform of each output V ₁ , V ₂ , V ₃ , V ₄ is expressed by the following equation (1)
It is approximated as shown in ~(4).

V ₁ αsin (2πx/P) …(1) V ₂ αsin (2πx/P-P/2) = −sin (2πx/P) …(2) V ₃ αsin (2πx/P+3P/4) = cos (2πx /P) ...(3) V ₄ αsin (2πx/P+P/4) = -cos (2πx/P) ...(4) Therefore, as mentioned above, V ₁ and V ₂ are determined by the voltage comparator 12. By comparison, the output _V5 of the voltage comparator 12 becomes a pulse signal with a period P as shown in FIG.

Similarly, pulse signals indicated by V ₆ , V ₇ and V ₈ are obtained from voltage comparators 13, 14 and 15, respectively. Note that when V ₅ is used as a reference, V ₆ is delayed in phase by P/4, V ₇ is delayed in phase by P/8, and V ₈ is delayed in phase by 3/8P.

Further, as shown in FIG. 5, the output V ₅ ,
V ₆ is exclusive OR circuit 16, output V ₇ and V ₈ are exclusive
When connected to the OR circuit 17, a pulse signal as shown in FIG. 8 is obtained. This pulse signal V _C and
As shown in the figure, it can be seen that two pulses are output in each cycle of _VD .

As explained above, according to the present invention, the number of pulses per rotation of the magnetic track can be reduced by 2 at the same magnetic pitch length as the conventional magnetic rotary encoder.
It can be doubled.

Although the present invention increases the number of signal processing circuits, it can be miniaturized by integrating the circuit.
It is possible to provide a magnetic rotary encoder that has approximately the same outer diameter as a conventional magnetic rotary encoder and has twice the number of pulses.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of the magnetic rotary encoder, Fig. 2 is a perspective view showing the structure of the magnetic detector with some parts omitted, and Fig. 3 is a diagram for generating pulse signals from the output of the magnetic detector. 4 is a diagram showing the waveform of the pulse signal output from the logic circuit of FIG. 3, and FIG. 5 is a circuit diagram showing the arithmetic circuit according to the present invention. Figures 6 and 7 are waveform diagrams showing voltage waveforms at predetermined points in the arithmetic circuit shown in Fig. 5, and Fig. 8 shows an output pulse signal of the arithmetic circuit shown in Fig. 5. FIG. 1...Rotating drum, 2...Magnetic detector, 3...
Arithmetic device, 8, 9, 10, 11... operational amplifier,
12, 13, 14, 15...voltage comparator, 16,
17...Exclusive OR circuit.

Claims (1)

[Scope of utility model registration request] A rotating drum is provided with first and second magnetic detection bodies disposed near a magnetic track magnetized with a predetermined magnetization pitch length at a predetermined interval with respect to the pitch length, In the magnetic rotary encoder, pulse signals having different phases are generated by the outputs of the first and second magnetic detectors, and the rotation angle of the magnetic track is detected by the pulse signals. a first arithmetic unit for non-inverting and amplifying the output of the first magnetic detector to obtain a first detection signal; and a first arithmetic unit for non-inverting and amplifying the output of the first magnetic detector to obtain a second detection signal. a second arithmetic unit for non-inverting amplifying the output of the second magnetic detector to obtain a third detection signal; a fourth calculation unit for inverting and amplifying and obtaining a fourth detection signal; a first voltage comparator for obtaining a first comparison signal from the first and second detection signals; and a third voltage comparator for obtaining a first comparison signal from the first and second detection signals.
and a second voltage comparator for obtaining a second comparison signal from the fourth detection signal, and a third voltage comparator for obtaining a third comparison signal from the first and third detection signals. , a fourth voltage comparator for obtaining a fourth comparison signal from the first and fourth detection signals, and a first output signal from the first comparison signal and the second comparison signal. and a second exclusive logic circuit for obtaining a second output signal from the third comparison signal and the fourth comparison signal. magnetic rotary encoder.