JPH06147920A - Magnetic encoder - Google Patents

Abstract

PURPOSE:To detect a magnetic drum rotating at high-speed and reduce the power consumption of battery so as to improve the service life of the battery when an incremental magnetic encoder is driven by the battery. CONSTITUTION:When a magnetic drum 1 rotates, an edge detecting circuit 10 detects its rotation and sends a signal to an intermittent/continuous drive switching circuit 11 for switching to intermittent or continuous driving in order to change the intermittent driving to the continuous driving, then an encoder can follow up the high-speed rotation. On the other hand, when the drum 1 does not rotate after a short while, the circuit 11 will change the continuous driving to the intermittent driving.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic encoder capable of calculating the rotational direction, the number of rotations, and the rotational position of a rotary shaft in an absolute format by using a magnetic incremental encoder.

[0002]

2. Description of the Related Art Conventionally, a magnetic rotary encoder for detecting a rotation speed and a rotation angle of a servo motor or the like is a magnetic drum magnetized with N and S poles at a pitch of resolution required on an outer peripheral surface as shown in FIG. 1 and a magnetoresistive effect element 2 arranged close to the outer peripheral surface of the magnetic drum 1 for detecting the external leakage magnetic flux, and the magnetoresistive effect element 2 is electrically
The resistance lines R1 to R8 as shown in FIG. 4 are arranged so as to obtain two outputs having a phase difference of 0 degree. Japanese Unexamined Patent Publication No. 60-218027 discloses a method of reducing power consumption by intermittently driving a magnetic sensor and a detection signal processing circuit by the magnetic sensor.

Next, a conventional example will be concretely described with reference to the block diagram shown in FIG. A pulse voltage is supplied to the magnetoresistive effect element 2 using a switching element 6 such as a transistor, an intermittent drive pulse generator 7 and a pulse generator 8 connected in series to the magnetoresistive effect element 2, and the magnetic field of the magnetic drum 1 at this time is supplied. The resistance change of the magnetoresistive effect element 2 due to is output as a signal corresponding to the rotation of the magnetic drum 1. This signal is shaped into a rectangular wave by the waveform shaping circuit 3, and converted into a pulse train whose rotation direction is determined by the multiplied signal output circuit 4. By inputting the pulse train whose rotation direction has been determined to the up-down counter 5, the number of rotations and the rotation position can be calculated in the absolute format. The reason for supplying the pulse voltage described above is to reduce the power consumption of the battery 9 attached to the outside as much as possible and improve the life of the battery.

[0004]

However, in the above-mentioned conventional configuration, when the magnetic pole of the magnetic drum 1 is changed and moved at a frequency higher than the switching frequency of the switching element 6 which supplies the pulse voltage to the magnetoresistive effect element 2, the magnetic resistance is changed. The output signal corresponding to the magnetic pitch cannot be obtained. Therefore, there is a problem in that the applied rotation speed can be limited when driven by a battery, and if the rotation speed is exceeded for some reason, a reliable signal cannot be obtained.

The present invention has been made to solve the above problems, and an object of the present invention is to make it possible to detect a reliable output signal even when the number of revolutions exceeds the applicable limit.

[0006]

To solve the above-mentioned problems, the present invention provides a magnetic drum, a magnetoresistive effect element for detecting an external leakage magnetic flux of the magnetic drum, and a pulse generator for generating a pulse having a predetermined frequency. An intermittent drive pulse generator that divides a pulse output from the pulse generator to generate a predetermined intermittent drive pulse; and a magnetoresistive effect element is switched by an output signal from the intermittent drive pulse generator. A switching element, and a waveform shaping circuit that shapes the waveform of the output signal obtained from the magnetoresistive effect element by the switching operation of the switching element,
A multiplication signal output circuit that outputs a multiplication signal whose direction is determined by the output signals from the waveform shaping circuit and the pulse generator, and an up / down unit that counts the output from the multiplication signal output circuit and detects the absolute position of the rotating body. An edge detection circuit for detecting at least one of the rising edge and the falling edge of the output signal of the multiplied signal output circuit, and switching between intermittent drive and continuous drive by the output signal from the edge detection circuit. The configuration is such that an intermittent / continuous drive switching circuit is added.

[0007]

According to the present invention, in the above structure, when the magnetic drum rotates while the encoder is driven by the battery, it is detected that the edge detection circuit has rotated, and the intermittent / continuous drive is switched between the intermittent drive and the continuous drive. A signal is sent to the drive switching circuit to change from intermittent drive to continuous drive, enabling high-speed rotation to be followed. If the magnetic drum is not rotating after a while, the intermittent / continuous drive switching circuit switches from continuous drive to intermittent drive to reduce the power consumption of the battery as much as possible and improve the battery life.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The same components as those described in the conventional example are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 1, the difference from the conventional example is that an edge detection circuit 10 for detecting at least one of the rising edge and the falling edge of the output signal of the multiplied signal output circuit 4 and the edge detection circuit 10 are provided. The point is that an intermittent / continuous drive switching circuit 11 for switching between intermittent drive and continuous drive by an output signal is added.

The operation of the above-described structure will be described. The magnetoresistive effect element 2 includes a switching element 6 such as a transistor connected in series to the magnetoresistive effect element 2 and an intermittent drive pulse generator 7.
Pulse voltage is supplied using the magnetic drum 1 at this time.
The resistance change of the magnetoresistive effect element 2 due to the magnetic field is output as a signal corresponding to the rotation of the magnetic drum 1. This signal is shaped into a rectangular wave by the waveform shaping circuit 3, and the multiplied signal output circuit 4
Is converted into a pulse train whose rotation direction is determined by. By inputting the pulse train whose rotation direction is determined to the up / down counter 5, the number of rotations and the rotation position can be calculated in the absolute format.

Therefore, the edge detection circuit 10 for detecting at least one of the rising edge and the falling edge of the output signal of the multiplied signal output circuit 4 and the intermittent / continuous drive for switching between the intermittent drive and the continuous drive by the output signal from the edge detection circuit. By adding the continuous drive switching circuit 11 newly,
When the magnetic drum 1 rotates while the encoder is driven by a battery, it detects that the edge detection circuit 10 has rotated, and a signal is sent to the intermittent / continuous drive switching circuit 11 that switches between intermittent drive and continuous drive. , From intermittent drive to continuous drive, it is possible to follow up to high speed rotation. Further, if the magnetic drum 1 is not rotated after a while, the intermittent / continuous drive switching circuit 11 can switch from continuous drive to intermittent drive to reduce the current consumption of the battery as much as possible and improve the life of the battery. .

[0012]

As is apparent from the above description, according to the present invention, when the encoder is driven by a battery, it is possible to follow high speed rotation by switching from intermittent driving to continuous driving, and the magnetic drum rotates. If it is not, it is possible to switch from continuous drive to intermittent drive and reduce the power consumption of the battery as much as possible to improve the life of the battery.

[Brief description of drawings]

FIG. 1 is a block diagram of a magnetic encoder according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional magnetic encoder.

FIG. 3 is a side view showing a positional relationship between a magnetic drum and a magnetoresistive effect element for detecting an external leakage magnetic flux.

FIG. 4 is an electric circuit diagram of a magnetoresistive effect element capable of electrically obtaining two outputs having a phase difference of 90 degrees.

[Explanation of symbols]

 1 magnetic drum 2 magnetoresistive effect element 3 waveform shaping circuit 4 multiplication signal output circuit 5 up / down counter 6 switching element 7 intermittent drive pulse generator 8 pulse generator 10 edge detection circuit 11 intermittent / continuous drive switching circuit

Claims (3)

[Claims] 1. A magnetic drum which is rotated by a rotating body and has N and S poles magnetized on an outer peripheral surface at equal intervals along a circumferential direction,
A magnetoresistive effect element that detects an external leakage magnetic flux of the magnetic drum, a pulse generator that generates a pulse of a predetermined frequency, and an intermittent pulse that divides a pulse output from the pulse generator to generate a predetermined intermittent drive pulse. A drive pulse generator, a switching element for switching the magnetoresistive effect element by an output signal from the intermittent drive pulse generator, and an output obtained from the magnetoresistive effect element by the switching operation of the switching element. A waveform shaping circuit that shapes the waveform of a signal, a multiplied signal output circuit that outputs a multiplied signal whose direction is determined by the output signals from the waveform shaping circuit and the pulse generator, and an output from the multiplied signal output circuit And an up-down counter for detecting the absolute position of the rotating body. An edge detection circuit for detecting at least one of a rising edge and a falling edge of a signal, and an intermittent / continuous drive switching circuit for switching between intermittent drive and continuous drive by an output signal from the edge detection circuit are added. A magnetic encoder that does. 2. A signal processing circuit of a magnetic encoder is a CM.
The magnetic encoder according to claim 1, which is formed of an OS device. 3. The magnetic encoder according to claim 1, wherein the power source of the magnetic encoder is a battery.