JPH02287210A - Zero point detecting system for incremental type magnetic encoder - Google Patents

Abstract

PURPOSE:To enable a stable zero point detecting operation to be performed by providing a zero point detecting magnetic code device to which poles N and S with predetermined magnetized widths are connected and a magnetoelectrically converting sensor which outputs an output signal corresponding to a zero point detection pulse. CONSTITUTION:Magnetic elements 20a and 20b of poles N and S, respectively, each having a magnetized width lambda/2 (lambda: magnetization pitch), are connected to each other in parallel in a zero point detecting magnetic code device 20. The body of an encoder which is made of a magnetic code recording medium is rotated and a magnetic code recorded in the recording medium is detected by a magnetoelectrically converting sensor 11. Thus, the rotating speed and rotational position of the magnetic code recording medium are detected. When the magnetic code device 20 is positioned as opposed to the sensor 11, the resistance values of the magnetoresistive elements 12 to 15 of the sensor 11 change in accordance with the magnetic fields of the elements 20a and 20b. Thus, the sensor 11 outputs a detection signal E generated when the magnetic code unit 20 is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a zero point detection method for an incremental magnetic encoder, particularly in a rotary encoder using a magnetoresistive element.

(Prior Art) Conventionally, incremental magnetic encoders have been widely used as magnetic rotary encoders. Some such magnetic encoders employ a zero point detection method as an interpolation method.

In the conventional zero point detection method, as shown in FIG. 4, a magnetic code section 10 for zero point detection consisting of, for example, an N-pole (or S-pole) magnetic element is provided at a predetermined position on a magnetic code recording medium that is the encoder body. It is being The magnetoelectric conversion sensor 11 is arranged to face the magnetic code recording medium, and detects the magnetic code unit IO for zero point detection at a position where the magnetic code unit 10 for detecting the zero point is opposed to the magnetic code unit 10 for detecting the zero point when the magnetic code recording medium rotates. .

Here, if the magnetized pitch of the magnetic grating (magnetic code) of the magnetic code recording medium is λ, then the magnetoelectric conversion sensor 11 is composed of magnetoresistive elements 12 to 15 each having an interval of λ/4. Moreover, the magnetization width of the magnetic code section 10 for zero point detection is λ
/2. The magnetoelectric conversion sensor 11 is configured such that a power supply voltage vcc is applied between the terminals of each of the connected magnetoresistive elements 12 to 15, and a detection signal E is output from an intermediate terminal.

When the magnetoelectric conversion sensor 11 detects the zero point detection magnetic code section 10 having a magnetization width of λ/2, it outputs a detection signal E having a voltage waveform as shown in FIG. This is an experimentally obtained voltage waveform. However, with the detection signal E shown in FIG. 3, when the comparator slices the detection signal E to a predetermined level and converts it into a pulse (zero detection pulse) P, an unnecessary noise pulse Pn is generated. Sometimes. Although such problems can be prevented to some extent by adjusting the slice level L, the slice level L may fluctuate due to disturbances such as temperature, humidity, or impact in the external environment of the encoder.

(Problems to be Solved by the Invention) In the conventional zero point detection method, when converting the detection signal E output from the magnetoelectric conversion sensor 11 into a pulse, the slice level at the time of conversion fluctuates due to disturbance etc. There is a problem that a stable zero point detection pulse is output.

An object of the present invention is to provide a zero point detection method for an incremental magnetic encoder that can reliably convert a detection signal output from a magnetoelectric conversion sensor into a pulse and perform a stable zero point detection operation.

(Means and Effects for Solving the Problems) The present invention provides an incremental type magnetic encoder in which, when the magnetization pitch of the magnetic lattice of a magnetic code recording medium is λ, the N pole of each magnetization width is λ/2, for example. This is a zero point detection method consisting of a magnetic code section for zero point detection and a magnetoelectric conversion sensor, which are configured by connecting the S and S poles. The magnetoelectric conversion sensor is configured to output a detection signal corresponding to a zero point detection pulse from an intermediate terminal of a circuit in which magnetoresistive elements are connected at intervals of, for example, λ/4.

With such a zero point detection method, a stable zero point detection pulse can be reliably obtained from the detection signal output from the magnetoelectric conversion sensor.

(Example) The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing the configuration related to the zero point detection method of the same embodiment. In FIG. 1, a magnetic code section 20 for zero point detection is provided at a predetermined position of a magnetic code recording medium, which is an encoder body (not shown). Magnetic code recording media include
A magnetic grating (magnetic code) is magnetized, for example, at a magnetization pitch λ. The magnetic code section 20 for zero point detection has each magnetization width of λ/
2, N-pole and S-pole magnetic elements 20a and 20b are connected in parallel. The magnetoelectric conversion sensor 11 is arranged to face the magnetic code recording medium, and detects the magnetic code part 20 for zero point detection at a position where the magnetic code part 10 for detecting the zero point is opposed to the magnetic code part 10 for detecting the zero point when the magnetic code recording medium rotates. . The magnetoelectric conversion sensor 11 includes magnetoresistive elements 12 whose spacing is λ/4.
It consists of ~15.

Next, the effects of this embodiment will be explained. In the magnetic encoder, a magnetic code recording medium, which is the encoder body, rotates, and the magnetic code recorded on the magnetic code recording medium is detected by the magnetoelectric conversion sensor 11. As a result, the rotational speed or rotational position of the magnetic code recording medium can be detected.

By the way, when the magnetic code section 20 for zero point detection provided on the magnetic code recording medium is located at a place opposite to the magnetoelectric conversion sensor 11, each magnetoresistive element 12 of the magnetoelectric conversion sensor 11
-15, the resistance changes according to the magnetic field of each magnetic element 20a, 20b. As a result, the magnetoelectric conversion sensor 11
A detection signal E is output when the zero point detection magnetic code section 20 is detected from the intermediate terminal. In this case, since the magnetic code unit 20 for zero point detection is configured as shown in FIG. 1, the detection signal E from the magnetoelectric conversion sensor IT has a nearly sinusoidal voltage waveform as shown in FIG. Become. This is an experimentally obtained voltage waveform.

In this manner, the magnetoelectric conversion sensor 11 outputs a detection signal E having a substantially sinusoidal waveform as shown in FIG. 2 when detecting the zero point detection magnetic code section 20. Therefore, for example, when converting the detection signal E into a zero detection pulse P by slicing the detection signal E at a predetermined slice level using a comparator, it is possible to convert the detection signal E into a reliable pulse as shown in FIG. can. That is, even if the slice level L changes somewhat due to disturbance to the magnetic encoder, only the necessary zero point detection pulse P can always be obtained without generating the noise pulse Pn as shown in FIG.

[Effects of the Invention] As detailed above, according to the present invention, in the zero point detection method of an incremental magnetic encoder, when a magnetic code section for zero point detection provided on a magnetic code recording medium is detected, magnetoelectric conversion is performed. A stable, almost sinusoidal detection signal can be obtained from the sensor. Therefore, even if the slice level during pulse conversion changes somewhat due to disturbance or the like, the detection signal output from the magnetoelectric conversion sensor can be reliably converted into a pulse. As a result, a stable zero point detection operation can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the embodiment, FIG. 3 is a waveform diagram related to the conventional zero point detection method, and FIG. The figure is a block diagram showing a configuration related to a conventional zero point detection method. DESCRIPTION OF SYMBOLS 10, 20... Magnetic code part for zero point detection, 11... Magnetoelectric conversion sensor, 12-15... Magnetoresistive element. Applicant's agent Patent attorney Takehiko Suzue 761

Claims (1)

[Claims] In an incremental magnetic encoder that detects a magnetic code section for zero point detection provided on a magnetic code recording medium and outputs a zero point detection pulse, a zero point is configured by connecting N and S poles of each predetermined magnetization width. a magnetic code section for detection;
The magneto-electric conversion sensor outputs a detection signal corresponding to the zero point detection pulse from an intermediate terminal of a circuit in which the magnetoresistive elements are connected with an interval between each magnetoresistive element being approximately half of the magnetization width. Zero point detection method for incremental magnetic encoder.