JP3331770B2 - Position detecting head and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an industrial machine, a machine tool,
The present invention relates to a position detection head used for detecting a position of a moving body in a precision measurement device or the like.

[0002]

2. Description of the Related Art FIG.
1, will be described with reference to FIG. In FIG. 11, 1 is a scale, 2 is a position sensor (position detection head), and 3 is a lead wire attached to the position sensor.

A conventional position sensor, as shown in FIG.
Position detection is performed when the scale 1 and the sensor 2 are relatively moved while the scale 1 and the sensor 2 are arranged so as to be parallel to the plane of the scale 1.

Therefore, the clearance (clearance) Cl between the sensor 2 and the scale 1 must be set in consideration of the thickness of the lead wire, and the distance A between the sensing part of the sensor and the scale surface is determined by the lead. It will be far by line 3.

In order to avoid this inconvenience, as shown in FIG. 12, the lead wire 3 attached to the sensor 2 is arranged so as to protrude to the outside of the opposing surface of the sensor 2 and the scale 1 and is located between the sensor 2 and the scale 1. It is conceivable to make the distance shorter, but in this case, the size of the sensor 2 must be increased.

[0006]

The sensor 2 shown in FIG.
If the width of the scale 1 is made the same and the size is reduced, a reduction in clearance (clearance loss) due to the lead wire 3 occurs, so that it is necessary to increase the wavelength of the scale formed on the scale. Position detection cannot be expected.

For example, when the reproducing wavelength is 0.2 mm, the clearance is about 0.14 mm. Therefore, when the thickness of the flexible substrate constituting the lead wire is 0.1 mm, the actually usable clearance is only 0.04 mm. Therefore, the flatness of the scale and the allowance for mounting the MR sensor are extremely severe.

For this reason, the protective cover cannot be attached to the surface, and the surface must be used with the surface bare, which is not practical.

SUMMARY OF THE INVENTION An object of the present invention is to provide a detection head which overcomes the above-mentioned drawbacks and allows a large clearance.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a position detecting head having a sensor section and a lead wiring section attached to a detection surface side of the sensor section. Provided is a position detection head in which a surface formed by a point closest to the position detection scale surface of the wiring portion is substantially parallel to the position detection scale surface. Further, as a method of manufacturing such a detection head, a holder for holding a sensor unit is fixed to a first assembly jig and formed integrally with the first assembly jig to define a position detection scale surface. A sensor part is placed on a surface defining the position detection graduation surface of the second assembling jig having a surface to be fixed, with the surface to which the lead wiring is attached facing the holder, and the sensor or the second assembling jig side By pressing the sensor part from above, a surface composed of a point closest to the position detection scale surface of the sensor part and the lead wiring part is defined, and the adhesive is filled and cured between the sensor part and the holder in that state. A method for manufacturing a position detection head including the step of causing the head to move.

[0011]

According to the present invention, in a position detection head having a sensor portion and a lead wiring portion attached to the detection surface side of the sensor portion, the detection surface of the sensor portion is similar to a conventional detection head (see FIG. 2). Is not parallel to the scale (position detection scale) plane, but is set by tilting the sensor section (see FIG. 1) and connecting the sensor section and the point closest to the scale of the lead wire section. (X plane) is parallel to the scale plane, so the usable detection distance (clearance)
Can be large. Therefore, the setting of the detection head becomes easy.

This makes it possible to use a narrow position detection wavelength region (short wavelength), which has conventionally been difficult to set a large clearance and difficult to set the detection head.
A high-resolution detection head can be obtained.

To manufacture the position detecting head of the present invention, it is only necessary to attach the sensor to the holder using a simple jig, so that the manufacturing cost is low.

[0014]

Next, an embodiment of the position sensor of the present invention will be described. FIG. 1 is a schematic diagram for explaining the basic concept of the position sensor of the present invention, wherein 1 is a scale, 2 is a sensor, and 3 is a lead wire.

The sensor 2 and the lead wiring 3 attached thereto are disposed so as to be inclined with respect to the scale plane C, and a point 2P closest to the C plane of the sensor 2 and a point 3P closest to the C plane of the lead 3 (X plane) is parallel to the C plane. θ is the angle between the X plane and the plane of the sensor 2,
ε is the distance between the X plane and the sensor center.

In order to compare the detection head of the present invention with a conventional detection head, FIG. 2 schematically illustrates the conventional detection head.

In the figure, A is the distance between the sensor 2 and the scale surface 1, that is, the clearance of the sensor itself, B is the thickness of the lead wire, CL is the actual clearance, and a is the distance from the sensor end to the center of the sensor detecting portion. The distance b indicates the distance from the sensor end to the lead wiring portion.

As is apparent from FIG. 2, the effective clearance CL usable in the conventional detection head is expressed by CL = AB ‥‥ (1).

On the other hand, in the sensor of the present invention, since the value of ε can be expressed by ε = (aB / b) cos θ (0 ° <θ <90 °) ‥‥ (2), CL ′ = A−ε From the relationship of ‥‥ (3) and the relationship of a <b, 0 ° <θ <90 °, and ε <B, CL <CL ′ ‥‥ (4), so that the detection head of the present invention is more conventional. The clearance can be made larger than that of the detection head.

In this case, in equation (2), a = 3 m
If m and b = 6 mm, the actual clearance CL 'in the equation (3) is 0.09 mm, and a protective cover of about 0.05 mm can be provided, which improves reliability and is practical. This also makes sensors that have been difficult to use in the past practical.

As is apparent from FIG. 1 and equation (3), in order to maximize the substantial clearance CL ', the sensor detecting section is formed such that the center of the sensor detecting section is located as close to the tip of the sensor 2 as possible. That is, it is preferable to minimize ε.

In the state where the distance ε between the X plane and the sensor center is minimized, in other words, in the state where the distance a from the sensor tip 2P to the center 2T of the sensor detector is minimized, one end of the sensor detector is connected to the sensor 2 However, if there is a possibility that inconvenience may occur when adjusting the position of the X plane, the end of the sensor detecting unit is located at a distance of, for example, about 0.5 mm from the sensor end 2P. What is necessary is just to form a sensor detection part like this.

Next, a specific structure of the detection head (sensor) will be described with reference to FIGS. In the detection head of FIG. 3, as the sensor 2, for example, a surface-to-surface type MR sensor (hereinafter, referred to as an MR sensor) is used. This MR sensor has a detecting element formed of a magnetoresistive element such as permalloy on a substrate such as glass or ceramic, and a lead wire 3 for supplying drive power and transmitting a detection signal is formed of a flexible substrate. You. The scale 1 (not shown) is made of a magnetic material, and magnetic scales are recorded precisely at equal intervals.

The sensor 2 is fixed to the holder 4 using an adhesive 5. A lead wire 3 made of a flexible substrate or the like connected to the sensor 2 is drawn out through a hole provided in the holder 4.

The detection head shown in FIG. 3 shows a case where the shape of the holder 4 is a flat plate, and is adjusted and fixed so that the tip of the sensor 2 comes closest to the scale.

FIG. 4 shows a case where the holder 4 is formed of a frame having a concave portion for accommodating the sensor 2, and the other structure is the same as that of FIG. 3A and FIG. 4A are cross-sectional views of the sensor, and FIG. 3B is a plan view of the sensor as viewed from below.

FIG. 5 shows still another structure of the sensor. 4, the sensor 2, the lead wire 3, and the holder 4 have the same structure as that described with reference to FIG. The sensor 2 is attached to the holder 4 with an elastic body such as a spring 7, and is fixed by pressing the sensor 2 with a screw 8 against the spring pressure from the holder 4 so as to support the sensor 2 at at least three points. .

At this time, the inclination of the sensor 2 can be adjusted by adjusting the three screws, and as described above, the clearance is adjusted so as to minimize the clearance loss.
5A is a cross-sectional view of the detection head, and FIG.
Is a top plan view.

Next, a method of reading a scale using the above-described detection head will be described. FIG. 6 shows a case where the scale 1 is read without contact.

The holder 4 supporting the sensor 2 is mounted on a mounting bracket 9 set to maintain a certain clearance. In order to adjust the position of the mounting bracket so as to have this height, a spacer equivalent to a clearance may be laid under the sensor unit to adjust the position.

In any case, the surface formed at the point closest to the position detection scale surface (scale surface) of the portion of the lead wire 3 and the portion of the sensor 2 must be set exactly parallel to the scale 1. No. In addition, a protective cover 10 is provided as needed to protect the lower surface of the sensor.

FIG. 7 shows an example in which position detection is performed by a contact method. In this example, the holder 4 is made of a sliding material, and the lower surface of the peripheral frame of the concave portion that houses the sensor 2 is a sliding surface.

The sensor unit is fixed by using the adjustment spacer with a clearance corresponding to the thickness of the spacer inside the holder 4 by a method described later with reference to FIG.

Thus, only the sliding surface of the holder comes into contact with the scale, and the sensor section and the wiring section do not come into contact with the scale. According to this structure, the surface formed at the point closest to the position detection graduation surface of the sensor 2 and the lead wire portion is set parallel to the sliding surface of the holder 4, so that the state is determined when the position is detected. Is also easily reproduced.

The holder 4 is supported by a carrier 13 by a support spring 12 in order to perform good position detection while always keeping the sliding surface in contact with the scale surface. Or a pressure spring 11 may be used.

FIG. 8 shows another example of the case where the position is detected by the contact method. The difference from the detection head of FIG.
0 is provided, and the sliding piece 14 is attached.

In the detection head shown in FIG. 7, the holder 4 is made of a sliding material. However, the entire holder need not be made of a sliding material, and only the sliding surface may be made of a sliding material. Further, by attaching the sliding piece, only the sliding portion can be made of a sliding material. Note that a sliding member, a bearing, or the like may be used as the sliding means.

Next, a method of manufacturing the detection head of the present invention will be described. FIG. 9 shows an example of how to assemble the detection head of the present invention. In the figure, the assembly jig (A) and the assembly jig (B) are integrated.

The inner plane of the assembly jig (B) reproduces the scale surface, and the holder 4 is fixed to the assembly jig (A). In this state, the sensor 2 with the lead wire 3 is arranged between the holder 4 and the assembly jig (B), and the sensor 2 is pressed from the holder 4 or the assembly jig (A) with a set screw 17. The method of pressing is not limited to a screw, and a spring or the like may be used.

In this state, an adhesive is filled between the holder 4 and the sensor 2 and cured. The push screw may be left as it is or may be removed. Instead of filling the adhesive between the holder 4 and the sensor 2, the adhesive is previously applied between the holder 4 and the sensor 2, and the position of the sensor is determined by the surface of the assembly jig (B) and the set screw 17. May be fixed.

With this arrangement, the surface closest to the position detection graduation surface of the sensor portion and the lead wire portion is set in parallel with the assembly jig (B), and is indicated by H1 in FIG. The dimensions and intersections between the upper surface of the holder 4 and the surface of the sensor 2 parallel to the scale including the point closest to the scale 1 can also be set precisely.

FIG. 10 shows how to make a detection head having the structure shown in FIG. Although a head having this structure can also be made by the method shown in FIG. 9, another method will be described here.

The integrated jigs (C) and (D) are used as assembly jigs. The inner plane of the assembly jig (D) reproduces the scale plane. The holder 4 is pressed against the assembly jig (D) by a pressing screw 18 provided on the assembly jig (C). Note that a spring may be used as a pressing method.

The sensor 2 to which the lead wire 3 is attached is arranged between the holder 4 and the assembling jig (D), and the sensor 2 is pressed against the assembling jig (D) from the holder 4 or from the outside with a push screw 17. In this case, a spring may be used as a pressing method.

An adhesive is filled between the holder 4 and the sensor 2 while being pressed in this manner, and is cured. After curing, the push screw may be left as it is or may be removed.

Further, if the adjusting spacer 19 is provided below the wiring lead 3 and the sensor section 2, the adjusting spacer 19 can be mounted inside the lower surface of the holder 4 by the thickness of the spacer, thereby protecting the sensor in the lateral direction. .

Thus, the sensor 2 and the lead 3
Closest to configured surface of the position detecting scale plane (X plane) is set parallel to the assembly jig (C) and (D), precisely set to scale shown in FIG. In H _2, which is set in advance can do.

As described above, with respect to the position detecting head of the present invention,
Although the embodiment has been described, the position detecting head of the present invention is not limited to the MR element but may be a Hall element. Further, the present invention is similarly effective in the case of a capacitive type or an optical type head.

[0049]

Since the position detecting head of the present invention has the above-described structure, a usable detecting distance (hereinafter, referred to as a clearance) can be increased, so that setting of the position detecting head becomes easy.

According to the position detecting head of the present invention,
Conventionally, a large clearance cannot be obtained, and a narrow position detection wavelength region, which has been difficult to set the detection head, can be used. Therefore, higher precision and higher resolution can be achieved.

No special mechanism or place is required to manufacture the position detecting head of the present invention, and therefore the head can be miniaturized easily and at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a basic concept of a detection head of the present invention.

FIG. 2 is a schematic diagram showing a conventional detection head.

FIG. 3 is a schematic view showing an embodiment of the detection head of the present invention.

FIG. 4 is a schematic view showing another embodiment of the detection head of the present invention.

FIG. 5 is a schematic view showing still another embodiment of the present invention.

FIG. 6 is a schematic diagram showing how to attach the detection head of the present invention when used for non-contact reading.

FIG. 7 is a schematic diagram showing how to mount the detection head of the present invention when used for contact reading.

FIG. 8 is a schematic diagram showing how to mount the detection head of the present invention when used for contact reading.

FIG. 9 is a schematic view showing an example of a jig used for manufacturing the detection head of the present invention.

FIG. 10 is a schematic view showing another example of a jig used for manufacturing the detection head of the present invention.

FIG. 11 is a schematic view showing the structure of a conventional detection head.

FIG. 12 is a schematic view showing the structure of a conventional detection head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scale 2 Sensor 3 Lead wire 4 Holder 5 Adhesive

Continuation of front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G01D 5/00-5/62 G01B ⁷ /00-7/34 G01P 1/00-3/80

Claims (2)

(57) [Claims] 1. A position detecting head having a sensor portion and a lead wiring portion attached to a detection surface side of the sensor portion, a surface formed by a point closest to a position detection scale surface of the sensor portion and the lead wiring portion. A position detection head configured substantially parallel to the position detection scale surface. 2. A first assembly jig for fixing a holder for holding a sensor portion, and a second assembly jig integrally formed with the first assembly jig having a surface for defining a position detection scale surface. An assembling jig comprising an assembling jig is prepared, a holder is fixed to the assembling jig, and the sensor portion is mounted with the surface on which the lead wiring is mounted facing the surface defining the position detection scale surface. By pressing the sensor unit from the holder or the first assembly jig side, a surface constituted by a point closest to the position detection scale surface of the sensor unit and the lead wiring unit is defined. A method for manufacturing a position detection head, comprising a step of curing an adhesive between the holder and the holder.