JP2641660B2 - Sensor target - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor target to be detected by a displacement sensor, and more particularly, to a sensor target which moves relative to a displacement sensor and whose position is detected by the displacement sensor.

[0002]

2. Description of the Related Art A mechanism for detecting a position of a moving sensor target by measuring a distance between a sensor head and a sensor target to be detected is known.
For example, it is disclosed in Japanese Utility Model Application Laid-Open No. 63-126817.

FIG. 7 shows the principle of such a conventional position detecting mechanism. That is, the distance (vertical distance) L between the sensor head 1 of the fixed displacement sensor and the sensor target 2 depends on the transport direction M1 of the sensor target 2.
Alternatively, it changes depending on the position in the M2 direction. Therefore, the distance L
If the characteristics of the transfer direction and the characteristics of the output signal of the displacement sensor are known in advance, the position of the sensor target 2 in the transfer direction can be specified from the sensor output.

[0004]

Here, if the output characteristic of the displacement sensor is linear, the sensor output (the value of the distance L)
It is easy to identify the sensor target position from
It is convenient. However, the output characteristics of the displacement sensor are not always linear. In order to obtain a linear output characteristic, it is often necessary to devise an amplifier or the like that amplifies the output of the sensor or to perform very complicated processing on the sensor output. .

[0005] On the other hand, there is a case where a non-linear sensor output is required contrary to the above. For example, when high-precision positioning or alignment is required, it is desirable that the amount of change in the sensor output with respect to the displacement of the sensor target is large when the sensor target is located at a position where particularly delicate positioning adjustment is required. However, in such a case, a nonlinear output (having a predetermined shape) is more appropriate than a linear output. In order to obtain a predetermined non-linear output in the conventional mechanism, there is a problem that a complicated operation such as devising an amplifier is required.

The displacement detecting device disclosed in Japanese Utility Model Laid-Open Publication No. Sho 63-126817, which has been exemplified as a prior art, has a wedge-shaped member manufactured separately from the carriage and attached to a side surface of the carriage to serve as a sensor target. However, when the wedge-shaped member is used as the sensor target as described above, it is difficult to process the inclination of the wedge-shaped member with high precision, and it is costly. Processing to provide an accurate curved surface is not easy, and when trying to obtain a non-linear output signal, complicated work such as devising an amplifier is required.

The present invention has been proposed in view of the above-mentioned prior art, and does not require complicated processing such as devising an amplifier or the like, and can be performed only by performing some processing on the sensor target itself. The purpose is to provide a sensor target capable of obtaining a sensor output.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a target which moves relative to a displacement sensor and whose position is detected by the displacement sensor, wherein the sensor target has a groove extending on the surface thereof in the direction of relative movement. Are formed, and the cross-sectional shape of the groove has a constant depth and a variable width.

Further, according to the present invention, in a sensor target which moves relatively to a displacement sensor and whose position is detected by the displacement sensor, the sensor target is provided on a surface thereof.
A groove extending in a relative movement direction is formed, and a groove having a constant width and a variable depth is used as the cross-sectional shape of the groove.

In practicing the present invention, the change in the width of the groove or the change in the depth of the groove is not limited to a linear change, but is changed non-linearly to obtain a non-linear output signal of the displacement sensor. This is of course also adopted.

Here, the displacement sensor may be of a type that performs measurement using a laser beam, a type that detects a distance between a sensor head and a sensor target surface by a change in capacitance, and other various types. In other words, if the sensor can measure the distance between the sensor head and the measurement point on the sensor target surface, no limiting condition is required.

[0012]

According to the sensor target of the present invention having the above-described configuration, the cross-sectional shape of the groove changes in the direction of movement relative to the displacement sensor, so that the output signal of the displacement sensor has desired characteristics. Since the configuration is as shown, a desired output characteristic can be obtained without changing the design specification of the sensor amplifier or requiring complicated processing. At that time, as a sensor target, a groove is formed on the surface of the sensor itself to cope with the problem.
In addition, the processing accuracy is easily obtained, and a highly accurate output can be obtained.
Particularly when it is desired to obtain a non-linear output signal, it is relatively easy to provide a curvature in the groove shape, and a desired shape can be easily obtained.

[0013] Then, since the desired sensor output characteristics can be obtained, the accuracy of the position control can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIGS. 1 and 2 show a first embodiment of the present invention. In FIG. 1, a sensor target indicated by reference numeral 10 is conveyed (moved) in the direction indicated by an arrow M or is traveling. Here, the sensor target 10 may be fixed and the displacement sensor may be moved in the direction opposite to the arrow M. In other words, the arrow M in FIG. 1 indicates the direction of movement of the sensor target 10 relative to the displacement sensor. Note that the transport direction (or relative movement direction) M of the sensor target is merely an example, and is not intended to be limited to the illustrated direction.

A groove 12 is formed in the surface of the sensor target 10 on the side of the displacement sensor facing the sensor head 1, and the groove 12 is formed in the transport direction M of the sensor target 10 (relative movement direction). It extends. FIG.
In the groove 12, the depth dimension H is constant, but the width dimension W is gradually narrowed toward the rear in the traveling direction M.

FIG. 2 shows the output of the displacement sensor detecting the sensor target 10 shown in FIG. Here, the symbol x on the horizontal axis indicates the amount of movement of the sensor target 10 in the traveling direction M. Symbol Vs is the voltage value of the sensor output.

As is apparent from FIG. 2, the sensor output is linear due to the shape of the groove 12.

FIGS. 3 and 4 show a second embodiment of the present invention. Although the first embodiment shows a structure for obtaining a linear sensor output, the second embodiment shown in FIGS. 3 and 4 is for obtaining an output which is non-linear and optimal for control.

In FIG. 3, a groove 22 is formed on the surface of the sensor target 20. The sensor target 20 is moved in the traveling direction M while the sensor head 1 is moving.
It is measured in.

As in the case of the first embodiment, the depth H of the groove 22 is constant, but the width of the groove 22 is changed.
However, unlike the first embodiment, the width W is the smallest at the center of the sensor target 20 in the traveling direction M, and the width W gradually increases toward the front and rear in the traveling direction M.

As a result of forming the groove 22 in such a shape, the sensor output becomes non-linear as shown in FIG. In such output characteristics, the sensor target 2 at the position near the peak
The change amount of the sensor output Vs with respect to the displacement amount in the traveling direction M of 0 becomes extremely large. Therefore, it is convenient when highly accurate position detection such as alignment is required. Further, it is determined whether the sensor target 20 exists at a predetermined position by determining whether the sensor output Vs at the peak and the value of the x coordinate at that time are within a predetermined deviation. It is.

In the first and second embodiments shown in FIGS. 1 to 4, the depth of the groove is constant and the width is changed. However, the cross-section may be reversed. That is, in the third embodiment shown in FIG.
The depth dimension H is changed while keeping the width dimension (not shown in FIG. 5) of No. 2 constant.

Further, in the fourth embodiment shown in FIG. 6, the groove 42 of the sensor target 40 has a portion 43 in which the depth H changes in a curved shape, and has such a curved groove portion 43. Thus, the output characteristics of the sensor can be changed in a curved shape.

In the above embodiment, the case where the present invention is used for a positioning assist mechanism has been described. However, the present invention can be applied to the field of detecting the moving distance of a target or a sensor head. For example, when the sensor head is moving, if a sensor target is set on the fixed side, a sensor output corresponding to the groove shape of the target can be obtained. Then, the output is converted into the x coordinate (coordinate in the moving direction) of the sensor head with respect to the target, and the position coordinate of the sensor head or the moving speed of the sensor head can be detected.

[0026]

The present invention described above has the following excellent effects. (1) As a sensor target, a groove extending in the relative movement direction is formed on the surface thereof, and the cross-sectional shape of the groove is changed (the width dimension or the depth dimension is changed linearly or non-linearly). With the configuration, a desired displacement sensor output characteristic can be obtained. (2) Since a groove is formed on the surface of the sensor target itself to cope with the problem, the sensor target can be easily manufactured and the processing accuracy can be easily obtained as compared with a case where an inclined member is separately processed as a target. , And a highly accurate output can be obtained. (3) When it is desired to obtain a non-linear output signal, it is relatively easy to provide a curvature in the groove shape, and a desired shape can be easily obtained. Positioning accuracy and positioning time can be controlled by the magnitude of the curvature. (4) Since a groove is formed in the sensor target itself, the thickness of the sensor target can be made extremely thin, so that the sensor target can be reduced in weight and size. The present invention can be suitably applied to a transfer table of a magnetic levitation transfer device that is particularly required to be lightweight and compact.

(5) From the above, the accuracy of position control can be extremely easily improved, and the present invention can be applied to the field of detecting the moving distance of a target or a sensor head.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is a diagram showing output characteristics of a displacement sensor obtained by the first embodiment of FIG.

FIG. 3 is a perspective view of a second embodiment of the present invention.

FIG. 4 is a diagram showing output characteristics of a displacement sensor obtained by the second embodiment of FIG. 3;

FIG. 5 is a sectional view showing a main part of a third embodiment of the present invention.

FIG. 6 is a sectional view showing a main part of a fourth embodiment of the present invention.

FIG. 7 is a side view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sensor head 2, 10, 20, 30, 40 ... Sensor target 12, 22, 32, 42 ... Groove M ... Progress direction H ... Depth dimension W ... Width dimension

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuji Shirao 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture Inside Ebara Research Institute, Inc. (72) Inventor Satoshi Mori 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture No. Ebara Research Institute, Inc. (56) References JP-A-50-54352 (JP, A) JP-A-1-70811 (JP, A) JP-A 63-126817 (JP, U) JP-A 64-64 10619 (JP, U)

Claims (2)

(57) [Claims] 1. A target which moves relative to a displacement sensor and whose position is detected by the displacement sensor, has a groove formed in the surface of the sensor target, the groove extending in a relative movement direction. A cross-sectional shape having a constant depth dimension and a variable width dimension. 2. A sensor target which moves relative to a displacement sensor and whose position is detected by the displacement sensor, the sensor target has a groove formed on a surface thereof, the groove extending in a relative movement direction. A sensor target characterized in that the cross-sectional shape of the groove has a constant width and a varied depth.