JP2543299B2 - Magnetic encoder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic linear or rotary encoder.

[0002]

2. Description of the Related Art A magnetic linear encoder or rotary encoder is well known as a device for measuring length and the like.

For example, a magnetic linear encoder using an MR element is composed of a long magnetic recording medium and a magnetic detector for detecting the strength of a magnetic field. When a constant current is passed through this magnetic detector, it responds to changes in the magnetic field. The moving distance of the magnetic detector can be measured by detecting the frequency at which the voltage between the MR elements changes.

The magnetic rotary encoder is provided with a magnetic recording medium on the outer circumference of a drum of a rotating shaft instead of a long magnetic recording medium, and can detect the speed or position of the rotating shaft.

Magnetization wavelength of these magnetic recording media (FIG. 4)
And the signal wavelength detected by the magnetic detector (FIG. 5) is one series with the same wavelength.

Conventionally, the magnetization wavelength of the magnetic recording medium and the signal wavelength of the magnetic detector are the same. Therefore, when both long wavelength and short wavelength signals are required for position control of machines, etc., both encoders are combined, or one magnetic recording medium is magnetized with two series of short wavelength and long wavelength, Since each is detected by a separate magnetic detector and both output signals are combined to control the position, an error is likely to occur.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic encoder capable of obtaining two or more signal wavelengths from a series of signals including two or more different magnetizing wavelengths.

[0008]

DISCLOSURE OF THE INVENTION The present invention has solved problems when combining encoders of two or more signal wavelengths or outputting two series of signal wavelengths from one magnetic recording medium. It is an object of the present invention to provide a magnetic encoder in which a magnetic recording medium is magnetized with two or more different wavelengths in one series, and two or more signal wavelengths are obtained by a magnetic detector.
The configuration of the present invention for that purpose is a magnetic encoder as set forth in the claims.

That is, according to the present invention, in a magnetic encoder comprising a magnetic recording medium, a magnetic detector and a signal processing circuit, two or more wavelengths of a long wavelength and a short wavelength are superposedly magnetized in a series on the magnetic recording medium. The magnetic encoder is characterized by detecting two or more different signal wavelengths from a magnetic detector and dividing the detected signal wavelengths into two or more frequencies for output by a signal processing circuit.

The magnetic encoder of the present invention can be applied to, for example, detection of the amount of movement of the printer head of a printer printing machine. The amount of movement of the printer head is processed by a signal having a long wavelength up to the vicinity of the movement, and a small amount of movement is processed by a short wavelength, so that the movement is performed quickly and accurately.

More specifically, referring to the drawings, sin (0.1.times.L) + sin (10.times.L) L: A current of a distance (mm) from the origin is applied to a linear magnetic recording medium by a magnetic head. Then, two different wavelengths are superimposed and magnetized as shown in FIG.

The wavelength superposed on the magnetic recording medium and magnetized is read out by a magnetic detector (MR head) and output as a signal wavelength of voltage change per unit time as shown in FIG. 3 through a voltage differential amplifier. Magnetic recording medium and MR when reading
The relative moving speed of the head is 100 mm / sec. The signal wavelength of this voltage change is divided into a short wavelength and a long wavelength and output as shown in FIG. 1 by the signal processing circuit (filter circuit). If the magnetic recording medium and the magnetic detector are moving relative to each other at a constant speed, the signal wavelength becomes the frequency, that is, if the two signal wavelengths are superposed, the signal should be separated by the filter circuit for each frequency. You can

More specifically, the filter A in FIG. 1 is a high pass filter and the filter B is a low pass filter. Filter A 1000Hz, wavelength 0.1
A signal having a wavelength of 10 mm and a signal having a wavelength of 10 mm is extracted by the filter B.

These output signals can be transmitted to a control circuit for position control.

[0015]

As described above, according to the present invention, two or more signal wavelengths can be obtained from two or more different magnetized wavelengths in one series, so that the structure of the encoder can be simplified. Also,
More than one signal wavelength can be obtained with one encoder.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a process of dividing a signal wavelength of an MR head into a short wavelength and a long wavelength by a signal processing circuit,

FIG. 2 is an explanatory diagram of two wavelengths magnetized on a magnetic recording medium,

FIG. 3 is an explanatory diagram of two signal wavelengths detected by the MR head,

FIG. 4 is a magnetization wavelength magnetized to a magnetic recording medium at a conventional wavelength,

FIG. 5 is a signal wavelength similarly detected by the MR head.

Claims (3)

(57) [Claims] 1. A magnetic encoder comprising a magnetic recording medium, a magnetic detector and a signal processing circuit, wherein two or more different wavelength signals are recorded on the magnetic recording medium in a superimposed manner. Encoder. 2. The magnetic encoder according to claim 1, wherein two or more different wavelengths are superimposed and outputted as a magnetic detection signal. 3. The magnetic encoder according to claim 1, wherein an output signal of the magnetic detector is divided and output by a signal processing circuit for each frequency corresponding to the wavelength.