JPH0833307B2 - Position sensor axis - Google Patents

Description

TECHNICAL FIELD The present invention relates to a position sensor shaft used in an XY table, a stroke cylinder, or the like.

[Prior Art] A position sensor device is roughly divided into a position sensor shaft, a position detection sensor, and an output device. The detection method includes an incremental method and an absolute method.
If the position sensor shaft is of the incremental type, it has various band-shaped or dot-shaped patterns, bid marks, etc. on its surface. On the other hand, if it is an absolute system, it has a gray code or BCD code on its surface. The position detection sensor is one that is convenient for detecting a band-shaped or dot-shaped pattern on the surface of the position sensor shaft, a bid mark, a gray code, a BCD code, etc., for example, a core type, a solenoid type, a magnetic sensor element type, etc. Used from time to time.
The digital absolute system is provided with a plurality of position detection sensors, the number of which corresponds to the code.
The output device includes various devices that output a mere change situation by a simple coupling circuit such as a bridge, and are so-called microcomputers that also output a relative velocity and / or a relative acceleration as well as a relative position. If the latter microcomputer is an incremental type, it counts the input pulse from the position detection sensor one wave at a time from the origin and outputs it. In this case, one set of two position detection sensors is used to determine the directivity. Furthermore, in order to improve the resolution, it is usual to include at least one set of these position detection sensors. On the other hand, in the case of the absolute method, the input code from the position detection sensor is converted into the position quantity as it is to output the relative position, the relative speed or / and the relative acceleration. In this case, it is usual to include at least one position detection sensor.

[Problems to be Solved by the Invention]

As described above, there are various types of position sensor shafts, position sensors, and output devices. However, there is no known position sensor shaft or position sensor device having a simple structure even if the accuracy is sacrificed to some degree, and a structure for easily detecting the absolute position. For example, JP-A-62-35
Although the configuration of the position sensor disclosed in No. 202 is quite simple, the pattern of the position sensor axis is somewhat complicated even with this.

In view of the above problems, the present invention provides a position sensor shaft which has a simple structure and can detect a position with high accuracy, and can detect both an incremental type and an absolute type. With the goal.

[Means for solving the problem]

In order to achieve the above-mentioned object, the position sensor shaft according to the present invention comprises a position sensor shaft having a pattern that moves relative to a position detection sensor and has an electromagnetic characteristic different from that of the base material. By the sensor, in the position sensor axis for detecting the relative movement position by detecting the pattern, the pattern is a continuous pattern C1 in which the hardness continuously changes from high hardness to low hardness, and the hardness of the continuous pattern C1 It is characterized in that it is provided with an intermittent pattern C2 in which different predetermined hardnesses are arranged at a predetermined interval p in an overlapping manner.

[Action]

Generally, when a shaft material used for a position sensor shaft has a hardness, a chemical composition, or the like that is different from that of the base material, that is, when the material is deteriorated, the electric characteristics such as electric resistance and magnetic permeability, and magnetic characteristics change ( Hereinafter, these electromagnetic characteristics are simply referred to as characteristics). This will be described with reference to FIG. As shown in FIG. 2 (b), the alteration pattern C1 is characterized in that the hardness is continuously altered in the position detection direction from high to low or vice versa, so that the characteristics at each position are continuous. Changes to. Therefore, it is possible to know the stepless absolute position by detecting the characteristic at each position. On the other hand, as shown in FIG. 2 (a), the altered pattern C2 itself has a constant hardness and is provided at a predetermined interval p.
Therefore, the characteristic of the site of this alteration pattern C2 is different from the characteristic of the other sites C1 and C3. Therefore, this can be scanned and the number of changes in characteristics can be counted. By counting from the scanning start point, the distance from the scanning start point can be known. To know the directionality, it can be achieved by detecting the A phase and the B phase using two position detection sensors. In other words, alteration pattern C2
Is an incremental pattern. In the present invention, since the electromagnetic characteristics are obtained by the hardness, the pattern C1
The pattern C2 can be detected even if the pattern C2 is arranged so as to overlap. Therefore, in the present invention, both patterns C1 and C2 are arranged so as to overlap from the beginning. That is, the relationship between the position and the hardness is as shown in FIG. That is, it is possible to detect both absolute detection and incremental detection.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. The first embodiment will be described with reference to FIG.
An alteration pattern C1 having a hardness that continuously changes from high to low or vice versa in the shaft surface and in the detection direction ± X, and overlaps with this, and in the detection direction ± X and at a predetermined interval p is substantially constant. And the alteration pattern C2 having high hardness.
The relationship between the hardness and the position of the alteration pattern C1 is shown in FIG. 2 (b), while the relationship between the high hardness of the alteration pattern C2 and the position is shown in FIG. 2 (a). , C2 are shown in FIG. 2 (c). still,
The shaft material is SCM435H. The second example is the alteration pattern C.
The hardness of C1 and C2 is lower than that of the base metal. Incidentally, the impartation of high hardness or low hardness to each of the altered patterns C1 and C2 will be described. The alteration pattern C1 is, in the above example,
A hardness gradient was applied by Jominie one-side quenching. other,
A hardness gradient may be imparted by controlling the carburizing depth by flowing C gas from one end during carburizing. On the other hand, alteration pattern C2
In the above example, the alteration pattern of high hardness was obtained by quenching with a laser beam. For low hardness, normalization may be performed. The heat treatment means need not be limited to a laser beam, and may be an electron beam or a plasma beam, or after covering the position sensor axis with a slit mask,
You may use flame, plasma, etc. The third embodiment is
As shown in FIG. 4, the alteration patterns C1 and C2 over the entire surface of the above embodiment are replaced with alteration patterns C1 and C2 of only a part in the detection direction X. By the way, as the position detecting sensor of the third embodiment, the position of the core type or the magnetic sensor element type which detects only the aimed part is more than the position detecting sensor of the all-round solenoid type which is averaged and the sensitivity is lowered. It is desirable to use a detection sensor. An example of detection using the above embodiment will be described with reference to FIG. 3. The position sensor shaft 1 of the first embodiment and the alteration patterns C1 and C2 of the position sensor shaft 1 are provided so as to face each other. At least 1
The position detection sensor 2 includes a plurality of position detection sensors 2 and a microcomputer 3 that stores in advance the relationship between the magnetic characteristic value based on the hardness of the alteration pattern C1 and the absolute position and the predetermined interval p of the alteration pattern C2. The signal S1 of the magnetic characteristic value based on the hardness of the altered pattern C1 is input from 2, and this is compared with the previously stored relationship between the magnetic characteristic value based on the hardness of the altered pattern C1 and the absolute position,
While obtaining the absolute position x corresponding to this,
After that, the relative movement ± ix of the position sensor axis 1 and the position detection sensor 2 causes the alteration pattern C2 to change from the position detection sensor 2.
The number n of the magnetic characteristic value signals S2 _{1 to} S2n based on the hardness is input, and this is multiplied by the previously stored predetermined interval p, and the result (± np≈ ± ix) is set to the absolute position ax. Addition (X = x ± np) is performed, and the calculated values of the relative position X between the position sensor axis 1 and the position detection sensor 2 and the relative velocity or / and the relative acceleration are output based on this. It should be noted that in the above-mentioned examples, all the characteristics have been described focusing on the magnetic characteristics based on hardness. On the other hand, it may be configured to detect a change in electric resistance based on hardness. Further, the quality may be changed by hardness, carburizing, nitriding, alloying or the like.

〔The invention's effect〕

As described above, according to the present invention, it is possible to detect both an incremental value and an absolute value with a simple configuration of the continuous pattern C1 whose characteristics change continuously and the intermittent pattern C2 whose characteristics change intermittently. Further, in the present invention, since the characteristic is given by hardness, the pattern C2 can be detected even if the pattern C2 is arranged so as to overlap the pattern C1. Therefore, both patterns C1 and C2 have a high degree of freedom in arrangement, and therefore the degree of freedom in arranging the detection head can be increased. Further, it can be suitably applied when a member having a surface hardness such as a cylinder rod is used as the position sensor shaft.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the configuration of the position sensor shaft according to the present invention. FIG. 2 is a characteristic graph for explaining the relationship between the electromagnetic characteristics and the position of the alteration pattern of the position sensor shaft according to the present invention. Therefore, (a) is a characteristic graph relating to the alteration pattern C2, (b) is a characteristic graph relating to the alteration pattern C1,
(C) is a characteristic graph obtained by combining these (a) and (b). FIG. 3 ... Diagram for explaining the configuration of the position sensor device according to the present invention. FIG. 4 ... Position sensor shaft according to the present invention. Configuration diagram of the third embodiment of 1 ... Position sensor axes C1, C2 ... Alteration pattern 2 ... Position detection sensor 3 ... Microcomputer S, S1, S2n ... Electromagnetic characteristic signal X ... Detection direction

Claims (1)

[Claims] 1. A position sensor shaft comprising a pattern that moves relative to the position detection sensor and has an electro-magnetic characteristic different from the electro-magnetic characteristic of the base material.
In the position sensor axis for detecting the relative movement position by detecting the pattern, the pattern has a continuous pattern C1 in which the hardness continuously changes from high hardness to low hardness, and a predetermined hardness different from the hardness of the continuous pattern C1. Hardness is a predetermined interval p
The position sensor shaft is characterized in that the position sensor shaft is provided with an intermittent pattern C2 that is arranged in a stack.