JPH01235812A - Production of magnetic type rotary encoder - Google Patents

Abstract

PURPOSE:To uniformly magnetize a shaft by fixing the end of the shaft on the side opposite to the side where the shaft is supported by a bearing to the rotary shaft of a magnetizing machine and magnetizing a magnet while rotating the same. CONSTITUTION:The shaft 12 is passed through the magnet 11 and is fixed thereto. The shaft 12 is mounted to a precision lathe and is worked on the circumferential face in a manner as to prevent the magnet 11 from running off in a radial direction. This shaft is mounted via the bearing 13 to a housing 14. The shaft 12 on the opposite side of the bearing 13 is fixed to the rotary shaft 18 of the magnetizing machine and is magnetized while the magnet 11 is rotated by a magnetic head 17. The magnetized signal is detected as an electric signal by an MR element 16 mounted to a supporting base 15. The uniform magnetization without the run-off of the magnet is thus executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a position detection device, and more particularly to a magnetic rotary encoder device using a magnetic sensor.

Conventional rotary encoders are rapidly gaining popularity as position detection devices for human equipment such as robots and automatic assembly machines. Currently, optical rotary encoders are the mainstay in this field, but magnetic rotary encoders have recently attracted attention due to their reliability against condensation, high-speed response, and low cost.

The structure and manufacturing method of a conventional rotary encoder will be explained using FIGS. 2 and 3.

In the figure, a shaft 2 is attached to a cylindrical magnet 1, and the circumferential surface of the magnet 1 is rough-finished. Next, the shaft 2 is attached to the housing 4 via the bearing 3, and while rotating the shaft 2 in this state, the circumferential surface of the magnet 1 is precisely finished using a precision lathe to prevent runout, and the radial direction of the magnet 1 is Make sure there is no vibration. After this, the circumferential surface of the magnet 1 is thinly magnetized while rotating the magnet 1.

Next, by arranging a ferromagnetic thin film magnetoresistive element (hereinafter referred to as MR element) 6 fixed to the support base 6 in the vicinity of the magnetized magnet 1 and opposing it, the output of this MR element 6 is amplified and the waveform It was reshaped and used as a necessary signal.

Problems to be Solved by the Invention Since rotary encoders used in the field of FA equipment require high precision, the rotary encoder has several thousand poles of magnetization, and its magnetization pitch is as small as several tens of micrometers.

The gap between the magnet and the magnetizing head must be several μm. Therefore, in rotary magnetization in which the magnet is magnetized while rotating, it is necessary to limit the deflection in the radial direction to several μm.

Conventionally, for the above reasons, in order to suppress radial runout, after assembly was completed, the housing was fixed and the magnet was rotated via the shaft, while the magnet was machined with a lathe. Also, if you assemble the magnet after precision processing.

Rotational runout increases due to variations during assembly.

There was a problem that variations occurred in magnetization.

The present invention is intended to solve these problems.

The purpose is to enable uniform magnetization.

Means for Solving the Problems To achieve this object, the present invention provides a magnetic rotary encoder device in which a shaft is fixed through a magnet, and the shaft is rotatably supported by a bearing.
The end of the shaft opposite to the side supported by the bearing is fixed to the rotating shaft of a magnetizer, and the magnet is magnetized while rotating.

Effect: With this configuration, the shaft is rotated and magnetized by stirring, and uniform magnetization can be achieved without vibration of the magnet.

EXAMPLE An example of the present invention will be described below with reference to FIG. FIG. 1 is a sectional view of a magnetic rotary encoder according to an embodiment of the present invention, in which a shaft 12 is fixed through a magnet 11, and the shaft 12 is mounted on a precision lathe to prevent the magnet 11 from wobbling in the radial direction. The circumferential surface is processed and attached to the housing 14 via the bearing 13.

Next, the shaft 12 on the opposite side of the bearing 13 is fixed to the rotating shaft 18 of a magnetizer, and magnetization is performed by the magnetic head 17 while rotating the magnet 11.

The magnetized signal is detected as an electric signal by the MR element 16 attached to the support base 15.

After magnetization if necessary, the shaft 12 may be cut at the dotted line portion.

Effects of the Invention As described above, according to the present invention, by precisely machining the magnet using the shaft as a reference, and even when magnetizing it once, the magnet is rotated and magnetized using the same point as a reference, thereby achieving uniform magnetization without vibration of the magnet. A high-precision rotary encoder can be obtained, and since the process is not as complicated as in the past, an inexpensive product can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view for explaining a method of manufacturing a rotary encoder according to an embodiment of the present invention, FIG. 2 is a perspective view showing a state in which a magnet is fixed to a shaft in a conventional manufacturing method, and FIG. FIG. 2 is a perspective view of a rotary encoder. 11...Magnet, 12...Shaft, 13
...Bearing, 14 ...Housing,
16... Support stand, 16... MR element, 1
7... Magnetic head, 18... Rotating shaft of the magnetizer. Figure 1

Claims (1)

[Claims] In a magnetic rotary encoder device in which a shaft is fixed through a magnet and the shaft is rotatably supported by a bearing, the end of the shaft opposite to the side supported by the bearing is fixed to the rotating shaft of a magnetizing machine, A method for manufacturing a magnetic rotary encoder characterized by magnetizing a magnet while rotating it.