JPS6222403B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a magnetic scale device, in particular, a magnetic scale device having a reference point (absolute origin) magnetizing body within the effective length measurement, having a simple and compact configuration, and also realizing improved wear resistance. Regarding the improvement of

Conventionally, measuring devices that use a magnetic scale with a magnetic grating have generally calculated measured values by counting the pulse signals obtained for each unit of movement between the magnetic scale and the detection head, which are moved relative to each other. Incremental measurements are being carried out.
Such an incremental measuring device has the advantage of being simple and inexpensive, but has the disadvantage that all past position information is lost when the power is turned off. In order to compensate for this drawback, a reference point magnet is provided within the effective measurement length of the magnetic scale, and this is detected by a reference point detection head consisting of a magnetic sensor to obtain an origin signal, and a pseudo absolute is generated based on this origin signal. A system has been proposed that performs measurements based on this method.

In addition, in the measuring device described above, iron particles, etc. tend to adhere to the surface of the magnetic scale, and the above-mentioned iron particles, etc., may be caught between the magnetic scale and the detection head, which is moved relatively close to the magnetic scale. If this happens, the detection head and magnetic scale may be damaged.

For this reason, it has been proposed to house the scale detection head and the reference point detection head in a magnetically shielded case, cover the magnetic scale detection surface with a protective cover, and bring them into sliding contact with each other using a wiper.

However, the conventional magnetic scale device described above must be configured to avoid the influence of crosstalk due to the provision of the reference point magnet. That is,
In order to prevent the scale detection head from being magnetized by the signal magnetic field of the reference point magnet, it is necessary to increase the distance between the magnetic scale and the reference point detection head, and to make the magnetic shielding case have a double structure. Therefore, the configuration of the magnetic scale device becomes large and complicated.

In addition, normally, the reference point magnet is embedded in the scale base, and in order to form the magnet so that the detection surface of the magnet is flush with the scale magnetic medium surface, a hole or hole for embedding the magnet is formed in the scale base. Grooves require machining, which increases costs.

Furthermore, since the detection surface of the magnetic scale is exposed to the outside, there is a risk of wear and tear during use.

The present invention has been made to improve the drawbacks of the prior art, and includes providing a magnetic scale on one side of the inside of a scale base formed in a substantially U-shape, and a reference point magnet on the other side. The present invention is characterized in that the scale signal and the reference point signal are read out by a scale detection head and a reference point detection head which are arranged opposite to the magnetic body and are magnetically shielded from each other by a magnetic material.

The present invention will be described below with reference to embodiments shown in the drawings. In FIGS. 1 and 2, 1 is a scale base formed in a substantially U-shape, 2 is a magnetic scale for measurement, 3 is a reference point magnet, 4 is a detection head device;
5 is a head mounting plate, 6 is a cable, 7 is a protective cover, and 8 is a wiper.

A measuring magnetic scale 2 and a reference point magnet 3 are provided on the inner surface of the scale base 1, and a detection head device 4 is disposed between them. The detection head device 4 is supported on the fixed side by a head mounting plate 5, and a cable 6 is connected within the detection head device 4 for extracting signals from the head and supplying power for energization.

The scale base 1 is made of a magnetic material such as iron, and as described above, the scale magnetic medium and the reference point magnet can be directly fixed to the inner surface thereof, and if the sloped part 1' is provided, the scale magnetic medium and the reference point magnet can be fixed directly to the inside surface of the scale base 1. Effective in preventing intrusion of oil, etc. The scale magnetic medium is provided with perpendicular magnetic graduations by, for example, a longitudinal magnetic field recording method to form a magnetic lattice to form a magnetic scale 2.

The reference point magnet generator 3 is formed of a rare earth magnet, a rubber magnet, a plastic magnet, or the like, and generates a reference point signal magnetic field in the vertical direction from its surface. In addition, the scale magnetic medium is Cu, Ni, Fe, Cu.
It is made of rolled magnets using spinodal magnetic materials such as Ni and Co, and its surface is finished with a uniform flat surface.Since it is housed within the scale base, there is little risk of wear and tear, but it can be used as needed. It is effective to cover with a protective cover 7 made of a suitable resin or the like.

Further, a wiper 8 is attached to the bottom surface of the detection head device 4 facing the magnetic scale 2, and the wiper is made of an elastic material such as polyurethane or nitrile rubber, and its tip has a blade shape. ing. The blade-shaped portion of this wiper is in elastic contact with the surface of the magnetic scale 2, and as the magnetic scale 2 and the detection head device 4 move relative to each other, it slides on the magnetic scale surface and It acts to remove iron powder etc. attached to the surface.

Next, the detection head device 4 includes, for example, as shown in FIGS. 3 to 5, a scale detection head 9 facing the magnetic scale 2, a reference point detection head 10 facing the reference point magnet generator side, a magnetic head case 11,
It consists of non-magnetic covers 12, 13, a terminal plate 14, etc.

The magnetic head case 11 has an H-shaped cross section, and its upper and lower parts are covered with covers 12 and 1.
The scale detection head 9 is installed in one chamber, and the reference point detection head 1 is installed in the other chamber.
0 is housed in each detection head, and the signal line from each detection head is connected to the cable 6 at the terminal plate 14.

As mentioned above, the scale detection head 9 and the reference point detection head 10 are magnetically shielded from each other by the magnetic head case 11, and a closed magnetic path is formed between the magnetic scale 2 and the reference point magnetizing body 3, so that mutual interference is prevented. almost completely prevented.

Further, the head case 11 and the head mounting plate 5 can be integrally formed by precision casting, etc., resulting in an extremely simple structure.

Note that the magnetic scale 2 is not limited to a vertical magnetic field scale, and a magnetic grating may be formed on the scale magnetic medium by a transverse magnetic field recording method. In this case, the scale base is formed from a non-magnetic material.

In this manner, by the relative movement of the magnetic scale 2 and the reference point magnet generator 3 with respect to the detection head device 4, the magnetic field from the magnet generator is detected by the reference point detection head 10 to obtain reference point position information, and the magnetic field from the magnetic scale 2 is detected. Measurement position information detected by the scale detection head 9 in the signal magnetic field can be output as absolute position information based on the reference point position information.

FIG. 6 shows how to use this device to prevent cutting powder and the like from entering the scale. As shown in the figure, the part of the scale base 1 to which the detection head is not attached faces upward, and the head mounting plate 5 is arranged parallel to this part.

FIG. 7 shows an embodiment in which the magnetic scale itself has a dust-proof structure, and elastic curtains 15 and 16 are attached to both ends of the opening of the scale base 1.

FIG. 8 shows an embodiment of a unit type magnetic scale device having an integral structure with a scale head. In the figure, numeral 17 is a slider guided by the outer cylindrical surface of the scale base 1, and the detection head device 4 is attached to this slider.

As is clear from the above explanation, according to the present invention, the scale base is easy to mold, and since the scale base has a structure in which the magnetic scale, reference point magnetization resistance, and detection head device are housed, there is a risk of wear and tear. It is effective in terms of dustproofing and has a simple structure overall.

In particular, the reference point magnet can be attached to any position in the scale measurement direction on the inside surface of the scale base, and it is easy to create a closed magnetic circuit configuration in conjunction with the detection head, so compared to conventional magnetic scales. The distance between the two can be reduced, which is advantageous in terms of miniaturization.

Further, since there is no need to embed the reference point magnet in the scale base as in the conventional case, the molding process is simplified, which greatly contributes to cost reduction.

Further, by using a magnetic head case, the reference point detection head and the scale detection head can be configured in closed magnetic circuits independent of each other with respect to the reference point magnet generator and the magnetic scale, respectively, so that the magnetic shielding effect is extremely high.

In addition, it is extremely easy to create a waterproof and dustproof structure, and its effects are remarkable in practical use.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing a magnetic head device according to an embodiment of the present invention, FIGS. 2a and 2b, and 3.
FIGS. 4 and 5 are schematic diagrams showing the configuration of the detection head device in the above embodiment, and FIGS. 6, 7, and 8 are schematic diagrams showing other embodiments of the present invention, respectively. It is. 1...Scale base, 2...Magnetic scale,
3... Reference point magnetizing body, 4... Detection head device, 5
...Head mounting plate, 8...Wiper.

Claims (1)

[Claims] 1 A magnetic scale is installed on one side of the inside of a roughly U-shaped scale base, and a reference point magnet is installed on the other side, and a scale signal detection head is installed inside each of the roughly H-shaped magnetic head cases facing the scale and the magnet. and a reference point signal detection head are arranged to read out the scale signal and the reference point signal, and when reading out the signals, the scale signal and the reference point magnetizing body are configured to form mutually independent closed magnetic paths. A magnetic scale device characterized in that the scale base and head case are formed.