JPS63103909A - Scale for displacement detection - Google Patents

Abstract

PURPOSE:To obtain a high-accuracy scale of simple structure which causes no deformation error by fitting a reference scale member where a scale for displacement detection is formed and an auxiliary scale part in one body across the scale. CONSTITUTION:The reference scale member 10 is made of rectangularly sectioned thin-plate type glass and has the scale 12 for measurement consisting of many specific-pitch slits lengthwise on the surface 11. The auxiliary scale member 20 is made of the same material with the member 10 and has the same shape and the same size and is joined with the member 10 with an adhesive 18 across the scale 12 to constitute a scale 70. Then, longitudinal neutral axes to the deformation of the whole scale 70 in the directions of the thickness (t) and width W are Y-Y and X-X. Here, the scale 12 is provided on the axis Y-Y and divided equally in the width direction about the axis Y-Y. Thus, even if the scale 70 curves and deforms in the direction of the thickness (t), the overall length of the scale 12 is unchanged as well as the axis Y-Y and no error is generated. Further, even if it curves and deforms in the direction of the width W, no error is generated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a scale for displacement detection, and includes a reference scale member on which a scale for displacement detection is formed, and a displacement detector disposed opposite to the scale. It is used in a displacement detection device that relatively moves a q tB scale material in the longitudinal direction and detects the amount of relative movement displacement.

[Background technology and its problems]

It is known to measure physical dimensions such as length, weight, pressure, etc. by detecting the amount of linear displacement via a displacement detection device.

Conventionally, the above-mentioned displacement detecting device, for example, for length measurement, has had a structure as shown in FIG. 4.

In FIG. 4, an optical displacement detection device 100 includes a reference scale member 10 provided with a scale 12 forming an optical grating in the longitudinal direction of a surface 11, and an index having scales 34A and 34B facing the scale 12. Scale member 3
1. A displacement detector 30 formed from a photoelectric conversion means 36 including a light emitting/receiving device 37° 38, a slider 50 that supports the displacement detector 30 so as to be movable relative to the reference scale member 10, and a reference scale member 10 and a slider 50.

Note that the reference scale member 10 has an adhesive 45 inside the long groove 42.
It was fixed to the main body case 40 by.

Further, 51, 51, . . . are sliding members.

Therefore, for example, while fixing the main body case 40 to a stationary body 2 such as a machine tool, the opening 43 of the main body case 40
If the slider 50 is connected to the movable body 1 through the movable member 60 that passes through the slider 50, the displacement detector 30 detects the amount of relative displacement between the reference scale member lO and the slider 50, that is, the stationary body 2 and the movable body such as the machine tool. 1 could be detected, and the length of the workpiece could be measured.

However, the conventional displacement detection device 100 described above had the following problems.

First, there was a drawback in that the deformation of the reference scale member 10 made it difficult to guarantee a predetermined accuracy.

In other words, if the main body case 40 (especially the long groove 42) is bent due to machining defects, the stationary body 2 and the main body case 40
In cases where there is a difference in the coefficient of thermal expansion between
As shown in A), the reference scale member 10 is curved and deformed in its thickness direction. In this case, since the scale 12 is provided on the front surface 11 (or back surface 14) of the reference scale member 10, the reference scale member 10 when straight (φ=0)
, the surface angle is φ, the length of the surface 12 when the surface angle φ occurs is 1, and the thickness of the reference scale member 10 is L, then in the case of the deformation shown, L11=L − t s
in φ, which is equal to the length of the scale 12) will shrink.

Therefore, an apparent incremental error occurs when the displacement detector 30 (particularly the index scale member 31) moves assuming that the reference scale member 10 is straight. On the other hand, if it is bent in the opposite direction to that shown in FIG. 3(A), an apparent decrement error will occur. Furthermore, since the section modulus of the reference scale member 10 is large due to its shape, it may be curved in the width W direction as well, although it is relatively small (see FIG. 3(B)). However, in this case, the reference scale member 10 There is a problem in that if the deviation ila from the center line in the width direction to the scale 12 is large, errors are likely to occur. The larger the scale, the more important these things become.

Second, the displacement detection device 100 is used in various environments, and the selection thereof is at the discretion of the user.

Therefore, if dust, oil droplets, etc. adhere to the surface 11 of the reference scale member 10, especially the surface on which the scale 12 is provided, the amount of light received by the light receiver 38 will attenuate and fluctuate, and from this point of view as well, accuracy cannot be guaranteed. It becomes difficult.

In particular, if an organic solvent or the like is used to scrub adhesives or oils during manufacturing and assembly or periodic inspections, and strong friction is applied, the scale 12 itself will be damaged, making it even more difficult to ensure accuracy. For this reason, it is extremely difficult to achieve high precision by making the pitch of the scale 12 fine.

Thirdly, since the facing gap between the reference scale member 10 and the index scale 31 must be maintained at more than 10 μm, the slider 50 is moved between the sliding members 51, 51. ...
. . , and is generally guided directly to the surface 11 of the reference scale member 10. However, since the scale 12 occupies a large area on the surface 11, the remaining portion must be used for sliding guidance, resulting in a problem that the structure of the slider 50 and the sliding members 51, 51, etc. becomes complicated. was there.

[Purpose of the invention]

The present invention has been made in view of the above conventional problems, and its purpose is to provide a highly accurate displacement detection scale that has a simple structure and does not cause deformation errors.

(Means and effects for solving the problem 2) The present invention has the following features:
The above conventional problems, especially the first problem regarding the occurrence of errors that could be individually recognized as a result, were caused by the fact that measurement scales were provided on the surface of the reference scale member from a manufacturing standpoint. The aim is to eliminate the above problem by aligning the scale with the vertical neutral axis of the entire scale while enjoying the basic manufacturing benefits.

For this reason, a scale is formed by integrally attaching a reference scale member on which a scale for displacement detection is formed along the longitudinal direction of the surface and a small auxiliary scale member with the scale in between, and the auxiliary scale member is The above object is achieved by configuring the scale so that the vertical neutral axis with respect to deformation in the thickness direction and the scale can be made to coincide with each other.

Therefore, since a scale is constructed by integrally forming a reference scale member and an auxiliary scale member, and a scale is provided at a position that coincides with the vertical neutral axis for deformation in the thickness direction of this scale, the longitudinal direction of the scale is The scale length is constant as is the length of its vertical neutral axis.

Therefore, even if the scale is deformed, no error occurs and a predetermined detection accuracy can be guaranteed.

〔Example〕

An embodiment of the displacement detection scale according to the present invention will be described in detail with reference to the drawings together with a displacement detection device for implementing the same.

It should be noted that the same or similar parts as those of the conventional displacement detection device shown in FIG.

The displacement detection scale 70 of this embodiment is composed of a reference scale member 10 and an auxiliary scale member 20, as shown in FIGS. 1 and 2.

First, the emptied scale member 10 is formed from a thin plate glass having a rectangular cross section, and the surface 11 has a 100 mm diameter along the longitudinal direction.
Measuring scale 1 consisting of many slits with a pitch of 0 μm
2 are arranged. This slit is covered with vapor-deposited chromium band n! 2 by an enching method.

On the other hand, the auxiliary scale member 20 is similar to the reference scale member 10.
It has the same shape, dimensions, and is made of the same material as the glass.

The reference scale member 10 and the auxiliary scale member 20 formed in this way are arranged so that the scale 12 is arranged between the front surface 11 of the reference scale member IO and the back surface 24 of the auxiliary scale member 20 as shown in FIG. 1(A). The scale 70 is sandwiched between the scales 10 and 20 by joining them together using, for example, an ultraviolet curing adhesive 18, and as shown in FIG.
Configure. In this embodiment, the thickness of the scale 70 is 6
It is mm. Therefore, for the individual thickness of the reference scale member 10, the vertical neutral axis for deformation in the direction is Y+ −
Y+, width W, longitudinal neutral axis for force direction deformation is X, -
X, and the longitudinal neutral axis of the auxiliary scale member 20 for the single thickness deformation in two directions is Yx Yz,
The longitudinal neutral axis for deformation in the width w2 direction is X□-X2, but the longitudinal neutral axis for deformation in the thickness L direction of the entire integrated scale 70 is Y-Y, and the longitudinal neutral axis for deformation in the width W direction is becomes X−x. Here, scale 12
are provided on the joint surface of both scale members 10.20, that is, on the joint neutral axis Y-Y, and are equally sized in the width direction W with the longitudinal neutral axis Y-Y as the center. In addition,
Both scale members 10 and 20 are the same in shape and have a rectangular cross section, so Y + Y + and X, -X mouth Y z
Yz and X, -X, and Y-Y and X-X are the same.

Therefore, according to this embodiment, the adhesive 45 is placed inside the length ii 442 of the main body case 40 as shown in FIG. 4 above.
If the scale 70 is fixed in the direction of its thickness t due to improper machining of the main body case 40, a difference in the coefficient of thermal expansion between the stationary body 2 and the main case 4°, or deformation of the mounting means, the vertical neutral axis Similar to YY, the overall length of the scale 12 remains unchanged. In other words, since the number of slits existing within a predetermined length does not increase or decrease, errors due to deformation of the scale 70 do not occur.

Moreover, since the scale 12 is provided with equal size distribution along the longitudinal neutral axis Y-Y, even if there is a curved deformation in the width W direction, no error occurs.

Furthermore, since the scale 12 is sandwiched between both scale members 10 and 20 and is not exposed, adhesives and oils adhering to the front and back surfaces of the scale 70 during manufacturing assembly and periodic inspection must be cleaned using an organic solvent in a 7-bar manner. They can also be removed quickly and perfectly without damaging the GT12.

This means that the optical characteristics of the scale 70 can be maintained at their best, so that a predetermined detection accuracy can be guaranteed for a long period of time.

Furthermore, since the entire surface (or the entire back surface) of the scale 70 can be used as a contact surface for the sliding members 51, 51, etc., smooth sliding of the slider 50 can be ensured, and the slider 50, etc. can be slidably guided. Another effect is that the degree of freedom in designing the mechanism can be increased.

In the above embodiment, the auxiliary scale member 20 is formed of the same shape, size, and material as the reference scale member 10, but the point is that the scale 12 is the vertical neutral axis s! with respect to the deformation of the scale 70 in the thickness direction T! y I-Y1, the size, shape, material, etc. of the auxiliary scale member 20 can be arbitrarily selected from the relationship with the form of the reference scale member IO.

Further, although the scale 70 is shown in the case where it is used in the conventional transmission type optical displacement detection device 100 shown in FIG. 4, the structure of the displacement detection device lOO is not limited. It may also be a reflective type using one main scale and two index scales. Similarly, although the scale 12 is a slit forming an optical grating, the present invention is naturally applicable to capacitive or electromagnetic slits.

〔Effect of the invention〕

The present invention can provide a highly accurate displacement detection scale with a simple structure and no deformation errors.

[Brief explanation of the drawing]

FIG. 1 is an external view showing an embodiment of a displacement detection scale according to the present invention, in which (A) shows the state before integration, (B) shows it after integration, and FIG. 2 shows deformation in the thickness direction. FIG. 3 is an external view of a conventional reference scale member during deformation, where (A) shows deformation in the thickness direction and (B) shows deformation in the width direction. and FIG. 4 is a sectional view of a main part of a conventional optical displacement detection device. 10... Reference scale member, I2... Scale, 20...
...Auxiliary scale member.

Claims (3)

[Claims] (1) A reference scale member on which a scale for displacement detection is formed along the longitudinal direction of the surface and an auxiliary scale member are integrally attached with the scale in between to form a scale, and the auxiliary scale member is attached to the thickness of the scale. A scale for detecting displacement, characterized in that the vertical neutral axis with respect to directional deformation is made to coincide with the scale. (2) The displacement detection scale according to claim 1, wherein the auxiliary scale member has the same shape and is made of the same material as the reference scale member. (3) In claim 1 or 2, the scale is provided on the reference scale member at a position such that the scale is on the longitudinal neutral axis with respect to the deformation of the scale in the width direction. scale.