JP5646357B2 - Reference scale - Google Patents

Description

  The present invention relates to a reference scale based on the superordinate concept of claim 1.

  In order to measure a large length, a reference scale assembled from a plurality of partial members is used. The reason is that a reference scale having high measurement accuracy and long-term stability required today can be manufactured at a low cost only with a relatively short length.

  The reference scale according to Patent Document 1 is composed of a plurality of partial members arranged in order in the measurement direction on a support member. On the support member, these partial members are each fixed by an adhesive.

  According to Patent Document 2 starting from the present invention, a reference scale made up of a plurality of partial members arranged in order in the measurement direction is well known, and these partial members are adhesives at locations where they are brought into contact with each other. Are connected to each other. A contact portion where the two partial members are brought into close contact with each other forms a gap that expands in the measurement direction, and an adhesive is put into the gap. That is, the adhesive is put between the surface area of one partial member and the surface area of the other partial member, and the vertical direction of the surface areas facing each other is in the measurement direction. Commercially available adhesives have the property that they can shrink or expand by changing volume when cured, when they age, and when environmental conditions (temperature, humidity) change. When the volume of the adhesive in the gap changes, a force is applied to the two surface regions of the partial member facing each other, in which the adhesive is inserted. Such a force is directed in the measurement direction and may change the length of the partial member or move the partial member, which causes a measurement error during position measurement.

JP-A-1-282422 US Pat. No. 4,261,106

  An object of the present invention is to realize a reference scale for measuring a large length having high measurement accuracy that is stable over a long period of time.

  This problem is solved by a reference scale according to the features of claim 1 according to the present invention.

  Advantageous embodiments are obtained by means of the dependent claims.

  The reference scale according to the present invention has a measurement scale for measuring a position in the measurement direction. In order to expand the measurement range in the measurement direction, the reference scale is composed of a plurality of partial members, and these partial members are separated from each other by a first boundary surface facing each other at their connection points. An adhesive that forms and connects the partial members to each other is disposed in the gap. The first boundary surfaces facing each other extend in the measurement direction, and form a gap between the boundary surfaces in a direction perpendicular to the measurement direction, and in the gap, Adhesive is deployed.

  By such a measure, when the volume of the adhesive is changed by expansion or contraction, an effect that a force directed in the measurement direction cannot be applied to the partial member is realized. The partial member is prevented from being compressed, extended and moved, so that high accuracy of position measurement is stably ensured over a long period of time.

  The vertical directions of the first boundary surfaces of the partial members facing each other do not have a component toward the measurement direction.

  These partial members constitute second boundary surfaces that face each other at their connection locations. The vertical directions of the second boundary surfaces of the two partial members facing each other have components that are directed in the measurement direction. These opposing second interfaces are not provided with an adhesive connecting the partial members.

  It is advantageous to arrange the first boundary surfaces facing each other outside the measurement scale. For this purpose, advantageously, one of the two partial members has a cut at their connection point, into which the projection of the other partial member fits. Such incisions and protrusions constitute on the one hand at least two opposite interfaces extending in the measuring direction, which form a gap in which the adhesive is deployed and on the other hand relative to the measuring direction. At least one abutment that extends vertically and is not provided with adhesive. Such a contact point is in the area of the measurement scale and extends parallel to the longitudinal direction of the scale line of the measurement scale.

  When these incisions and protrusions are formed in a tongue shape, a pair of boundary surfaces extending in the measurement direction are formed in parallel to each other, and thus two gaps into which an adhesive is poured are formed. These notches and protrusions have two boundary surfaces arranged in parallel to each other extending in the measurement direction, and these boundary surfaces constitute the first boundary surfaces facing each other. And the 1st boundary surface which such two partial members mutually oppose forms two clearance gaps, and an adhesive agent is each arrange | positioned in those clearance gaps. These two gaps are arranged symmetrically with respect to the center line of the partial member.

  In particular, an adhesive flow stop is provided. The flow stop is constituted, for example, by a plurality of vertical pieces spaced apart from one another and the space between the vertical pieces forms a pocket for accommodating the adhesive.

  For high-accuracy position measurement, it is advantageous that the partial member is made of glass or ceramic glass, and the measurement scale on the partial member can be scanned photoelectrically.

  Further advantages and details of the present invention will become apparent from the description of the embodiments based on the attached drawings in the following.

Plan view of the connection part of two partial members of the reference scale when combined The top view of FIG. 1 in the state which combined the partial member

  1 and 2 illustrate the connection locations of two partial members 10 and 20 to be connected to each other on the reference scale. Each partial member 10, 20 has a measurement scale 1 provided for position measurement in the measurement direction X. The measurement graduation 1 is an incremental line graduation composed of an array in which graduation lines 3 having the same period P of several μm, particularly 10 μm or less, are arranged in the measurement direction X. As an alternative or in addition, the measurement scale 1 can also be an array with absolute coding parts, in particular scale lines with different widths arranged in the measurement direction X.

For high accuracy position measurement, the sub-members 10, 20 are advantageously essentially stable, resistant to bending and, advantageously, average thermal expansion in the temperature range of 0 ° to 50 °. It is made of a material having a coefficient α of 1.5 × 10 ⁻⁶ K ^{−1 or} less, and a so-called non-expandable glass or ceramic glass such as ZERODU® (registered trademark), SITAL (registered trademark), or ULE (registered trademark) is used. In this case, it is within 0.1 × 10 ⁻⁶ K ⁻¹ . For high-accuracy position measurement, the measurement scale 1 is configured so as to be able to scan photoelectrically, and is configured as an amplitude grating or a phase grating. For this purpose, the graduation line 3 of the measurement graduation 1 is advantageously configured to reflect light, in particular from a coating of the partial members 10, 20 made of a highly reflective material.

  As shown in FIG. 2, in the abutted state, that is, in the combined state, the two partial members 10 and 20 are connected to each other by bonding at their connection points. For this purpose, the end portions on the connected side of the two partial members 10, 20 have first boundary surfaces 11, 21 and 12, 22 facing each other extending in the measurement direction X in parallel with each other. The first boundary surface 11 of one partial member 10 and the first boundary surface 21 of the other partial member 20 that face each other form a gap 31 between them, and the adhesive 4 is placed in the gap. It is thrown. In this example, the partial members 10 and 20 have first boundary surfaces 12 and 22 that face each other and extend in the measurement direction X parallel to each other, and these boundary surfaces form a gap 32 therebetween. The adhesive 4 is put into the gap. These two gaps 31 and 32 face the direction perpendicular to the measurement direction X, that is, the Y direction. The thicknesses of the gaps 31 and 32 are each about 25 μm, and the bonding is advantageously performed over the entire width (in the Z direction) of the partial members 10 and 20, which width is preferably 2 mm or more It is. The adhesive 4 is, for example, a two-component epoxy resin adhesive.

  The first boundary surfaces 11 and 12 of one partial member 10 extend in the measurement direction X in parallel with each other, and therefore the vertical directions N11 and N12 of these boundary surfaces do not have components directed toward the measurement direction X, respectively. . The boundary surfaces 21 and 22 of the other partial member 20 facing the boundary surfaces 11 and 12 respectively extend in the measurement direction X in parallel with each other, so that the vertical directions N21 and N22 of these boundary surfaces are respectively Does not have a component toward the measurement direction X.

  Further, the two partial members 10 and 20 have second boundary surfaces 13, 23, 14, 24 and 15, 25 facing each other, and these boundary surfaces are in their vertical directions N13, N23, N14, N24, N15, and N25 extend so as to have components in the measurement direction X, respectively. These second interface surfaces 13, 23; 14, 24; 15, 25 are not provided with the adhesive 4 connecting the two partial members 10, 20. That is, the adhesive 4 is not poured into the gaps 33, 34 and 35 formed from the second boundary surfaces 13, 23; 14, 24; 15, 25, respectively. The adhesive 4 is formed by one or more boundary surfaces 11, 21 and 12, 22 of the partial members 10, 20 that do not have components whose vertical directions N 11, N 21 and N 12, N 22 are directed in the measurement direction X, or Only the gaps 31 and 32 are introduced.

  The advantage of such a measure is that if the volume of the adhesive 4 is changed in such a manner that the adhesive 4 contracts or expands, a force component directed in the measuring direction X cannot be generated on the partial members 10 and 20. . For this purpose, the adhesive 4 is arranged such that the vertical component is not held on the mutually facing surfaces of the two partial members 10, 20 extending in the measuring direction X.

  The two partial members 10 and 20 have the same cross section and extend at the same height (the height extending in the Z direction, i.e. towards the plane of the drawing). That is, the measurement graduations 1 of the partial members 10 and 20 are connected so as to exist in the same plane.

  The advantage of the configuration of the connection point illustrated here is that the contact point extending in parallel with the longitudinal direction of the scale line 3 is in the measurement scale 1, and the boundary surfaces 13 and 23 are in the measurement direction X at the contact point. It extends perpendicular to the direction, that is, in the Y direction. On the other hand, the first boundary surfaces 11, 21; 12, 22 are outside the measurement scale 1. In order to realize this, one of the partial members 10 has the cuts 5 at their connection locations, and the protrusions 6 of the other partial member 20 are fitted into the cuts. When these notches 5 and protrusions 6 are each formed in a tongue shape, they constitute a plurality of first boundary surfaces 11, 21 and 12, 22 arranged in parallel to each other extending in the measurement direction X. These first boundary surfaces 11, 21 and 12, 22 form two gaps 31, 32 extending in parallel to each other, and an adhesive for connecting the two partial members 10, 20 within these gaps 4 is deployed. The two gaps 31 and 32 extend mirror-symmetrically with respect to the center line M of the partial members 10 and 20.

  The gap 33 is adjusted so that the last scale line of the partial member 10 and the subsequent scale line of the partial member 20 are arranged at an interval corresponding to the period P. Therefore, the gap 33 can be made zero.

  If a fluid adhesive 4 is used, it is advantageous to provide a flow stop 7 that prevents the adhesive 4 from spreading when the adhesive 4 is applied. In the example shown, such a flow stop 7 is configured as a vertical piece of the partial member 20 protruding into the gaps 31 and 32 in the Y direction. In order to prevent the adhesive 4 from spreading in both directions + X and -X, it is advantageous to arrange the adhesive 4 between two such vertical pieces, respectively. Then, the two vertical pieces arranged at a distance from each other in the measurement direction X form a pocket for accommodating the adhesive 4 between them. Further, the vertical piece serving as the flow stop 7 constitutes a spacer for realizing gaps 31 and 32 having a predetermined width (in the Y direction) between the two partial members 10 and 20.

DESCRIPTION OF SYMBOLS 1 Measurement scale 3 Scale line 4 Adhesive 5 Cutting 6 Protrusion 7 Flow stop 10 Partial member 11 First boundary surface 12 of partial member 10 First boundary surface 13 of partial member 10 Second boundary surface 14 of partial member 10 Second boundary surface 15 of partial member 15 Second boundary surface of partial member 10 20 Partial member 21 First boundary surface of partial member 20 22 First boundary surface of partial member 20 23 Second boundary surface of partial member 20 Boundary surface 24 Second boundary surface of partial member 20 25 Second boundary surface of partial member 20 31 Clearance 32 Clearance 33 Clearance 34 Clearance 35 Clearance M Center line of partial members 10 and 20 N11 Vertical direction of boundary surface 11 N12 Boundary Vertical direction of surface 12 N13 Vertical direction of boundary surface 13 N14 Vertical direction of boundary surface 14 N15 Vertical direction of boundary surface 15 N21 Vertical direction of boundary surface 21 N22 Vertical direction of boundary surface 22 23 cycles X and Y directions in the vertical direction P gridlines 3 vertical N25 interface 25 in the vertical direction N24 interface 24 of the interface 23

Claims (9)

Reference scale with a measurement scale (1) for measuring a position in the measurement direction (X), the reference scale being assembled from at least two partial members (10, 20), The first boundary surfaces (11, 21; 12, 22) that face each other form a mutual gap (31, 32), and the adhesive (10) that connects the partial members (10, 20) to each other in the gap. In the reference scale where 4) is deployed,
The first boundary surfaces (11, 21; 12, 22) facing each other extend in the measurement direction (X), and are perpendicular to the measurement direction (X) between the boundary surfaces. Forming the gaps (31, 32) facing the surface, and the adhesive (4) being disposed in the gaps ;
There is a first boundary surface (11, 21; 12, 22) facing each other at the connection location of the partial members (10, 20), and the vertical direction (N11, N21, N12, N22) of these boundary surfaces is There is a second boundary surface (13, 23; 14, 24; 15, 25) opposed to each other at the connection location of the partial members (10, 20) without having a component toward the measurement direction (X). The vertical directions (N13, N23, N14, N24, N15, N25) of the boundary surfaces each have a component toward the measurement direction (X), and these second boundary surfaces (13, 23; 14, 14, 24; 15, 25) is not provided with an adhesive (4) connecting the partial members (10, 20);
A standard measure characterized by Together first boundary surface facing (11, 21; 12, 22) is, the scale of claim 1, characterized in that disposed outside the measuring graduation (1). One partial member (10) of the two partial members has a cut (5) at their connection point, and the protrusion (6) of the other partial member (20) is fitted into the cut. The reference scale according to claim 1 or 2 , wherein the reference scale is characterized. The notch (5) and the protrusion (6) have two boundary surfaces (11, 21; 12, 22) arranged in parallel to each other extending in the measuring direction (X), and these boundary surfaces are 4. The reference scale according to claim 3 , wherein the first boundary surfaces (11, 21; 12, 22) facing each other are formed. The first boundary surfaces (11, 21; 12, 22) facing each other of the two partial members (10, 20) form two gaps (31, 32) and are bonded to the gaps, respectively. Agent (4) is deployed,
These two gaps (31, 32) are arranged symmetrically with respect to the center line (M) of the partial members (10, 20);
The reference scale according to claim 4 . Measuring standard according to any one of claims 1 to 5, characterized in that the flow stop for the adhesive (4) (7) is deployed. 7. The flow stop (7) according to claim 6 , characterized in that it is constituted by vertical pieces spaced apart from one another in one of the partial members (10, 20). Reference scale. The reference scale according to any one of claims 1 to 7 , wherein the partial members (10, 20) are made of glass or ceramic glass. The reference scale according to any one of claims 1 to 8 , wherein the measurement scale (1) is configured to be photoelectrically scanable.

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