JP5885409B2 - Scale protection structure for displacement detection scale - Google Patents

Description

The present invention relates to a scale protection structure for a displacement detection scale, and more particularly to a displacement detection scale that is suitable for application when reducing output fluctuations generated in a linear encoder, arc encoder, rotary encoder, etc. due to the scale. It relates to the scale protection structure.

  Conventionally, for example, a linear encoder includes a scale 10 and a detector 20 disposed so as to face the scale 10 as shown in FIG. 1 and moves the scale 10 in a measurement direction indicated by a double arrow. Thus, the relative displacement between the scale 10 and the detector 20 is detected.

  In the conventional scale 10 constituting such an encoder, a scale portion 14 is patterned on one main surface of a glass scale substrate 12 by a film forming technique.

  In this way, the encoder used with the detector 20 facing the scale 10 mainly made of glass has a cover as shown in order to protect the scale portion 14 on the scale 10 from scratches and dirt. There is one in which the glass 16 is bonded and integrated with the scale 10.

JP 2002-318137 A

  However, in order to adhere and integrate the cover glass 16 to the scale 10 as described above, an adhesive layer (agent) in which the cover glass 16 is formed on the upper surface portion of the scale portion 14 as schematically shown in FIG. In the case of arranging and adhering to 18, the fluctuation of the encoder output outputted as the detection value from the detector 20 due to the uneven thickness of the adhesive existing in the measurement (movement) direction orthogonal to the width direction in the figure. There was a problem of causing.

  Patent Document 1 discloses a technique for preventing harmful coolant, oil, or the like from entering the scale electrode side by forming a coating layer on the scale electrode (scale portion) patterned on the substrate. Although disclosed, this scale structure also has a similar problem because an adhesive is used for joining the coating layer and the scale cover corresponding to the cover glass.

The present invention has been made to solve the above-described conventional problems, and is a displacement detection scale that can prevent output fluctuation of an encoder due to uneven thickness of an adhesive that bonds a cover glass to a scale portion. It is an object to provide a scale protection structure.

The present invention provides a scale protection structure for a displacement detection scale in which a scale portion formed along a relative movement direction with respect to a detector on a scale substrate is protected by a cover glass disposed on the upper surface thereof. glass, through the height defining portion disposed around the scale portion, said supported on the scale substrate, said height defining portion, the lower surface of the cover glass, the entire circumference of the graduation The film is formed in advance in the same thickness with a corresponding pattern, and the lower end of the film is in contact with the upper surface of the scale substrate. Further, the scale substrate and the cover glass are arranged around the height defining portion. The above-mentioned problems are solved by being bonded with an adhesive disposed in the above.

According to the present invention, the adhesive can be disposed all around the height defining portion, and the height defining portion and the scale portion can be formed of the same kind of metal. The thickness defining portion can be formed of a metal made of chromium, copper, or aluminum.

According to the present invention, since the cover glass is supported on the scale substrate via the height defining portion formed on the lower surface, the adhesive (layer) can be excluded from between the scale portion and the cover glass. Therefore, it is possible to eliminate the variation in the gap (interval) between the scale portion and the scale cover due to the uneven thickness of the adhesive, so that the gap can be made constant, and the encoder output of the displacement detection scale can be reduced. It becomes possible to stabilize.

Schematic sectional view showing the outline of a conventional encoder Cross-sectional view schematically showing the scale structure used in a conventional encoder The cross-sectional view which shows typically the scale structure of one Embodiment which concerns on this invention Sectional drawing corresponding to FIG. 3 which shows the characteristics of the manufacturing process of the scale structure of the said embodiment. The top view which abbreviate | omitted the middle typically showing the scale structure of the said embodiment

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 is a cross-sectional view corresponding to FIG. 2 schematically showing a scale structure of an embodiment according to the present invention, and FIG. 4 is a corresponding cross-sectional view showing the characteristics of the manufacturing process.

  The scale 10 according to the present embodiment is similar to the conventional one shown in FIG. 2 in that the scale portion 14 is formed by patterning on a glass scale substrate 12 by a normal film forming technique such as sputtering or plating, In order to protect the scale part 14, the cover glass 16 arrange | positioned by the upper surface (surface) side is provided.

  In the present embodiment, the height defining portion 30 is formed in advance in a pattern corresponding to the periphery of the scale portion 14 on the lower surface of the cover glass 16 in the figure as shown in FIG. Is formed. Next, the cover glass 16 in this state is lowered in the direction of the arrow, and the cover glass 16 in which the lower end of the height defining portion 30 is brought into contact with the upper surface of the scale substrate 12 is disposed around the scale portion 14. It is supported on the scale substrate 12 via the height defining portion 30. Thereafter, the scale substrate 12 and the cover glass 16 are further bonded together with an adhesive layer 32 formed by sealing an adhesive around the entire height defining portion 30.

The height defining portion 30 has a continuous shape on the lower surface of the cover glass 16 corresponding to the entire circumference surrounding the scale portion 14, as shown in the plan view of FIG. Although not shown, they are formed at the same height (thickness). Thus, the high adhesiveness with respect to the scale part 14 is securable by making it the same continuous height. Therefore, the surrounding adhesive can be easily sealed .

  The height defining portion 30 protects the scale portion 14 when the scale portion 14 is formed mainly by depositing chromium (Cr), copper (Cu), aluminum (Al), or the like. The cover glass 16 is also made of the same kind of metal such as chrome, copper, aluminum, etc., and a film formation pattern having a thickness slightly exceeding the scale portion 14 is formed and arranged in the predetermined position as described above. It is also effective to secure stability against temperature changes.

  Here, as a suitable thickness of the scale part 14, 100 nm to 30 μm, and as a suitable thickness of the height defining part 30, a gap between the cover glass 16 and the scale part 14 is 30 nm to 0.1 mm. The thickness which becomes a grade can be mentioned, respectively. However, it depends on the characteristics of the encoder to be applied.

  Thus, since the thickness unevenness of the film formation pattern formed on the scale substrate 12 and the cover glass 16 is generally about 10 nm to 50 nm, the thickness defining portion 30 as well as the scale portion 14 has a very stable thickness. Can be formed. Moreover, in order to support the height defining portion 30 on the scale substrate 12, an adhesive is used between the scale substrate 12 and the height defining portion 30 and between the height defining portion 30 and the cover glass 16. Not. Accordingly, the variation in the gap between the scale portion 14 and the cover glass 16 in the measurement (moving) direction can be greatly reduced, and the adhesive layer 18 of FIG. It is possible to surely prevent the fluctuations.

  Further, as described above, the adhesive layer 32 is disposed around the entire height defining portion 30 and sealed, which can prevent foreign matter from entering the scale portion 14. If there is no need for the above, the adhesive layer 32 may be partially disposed around the periphery. In addition, as an adhesive for forming the adhesive layer 32, ordinary acrylic, epoxy, or the like can be used. In particular, when the entire periphery of the height defining portion 30 is sealed, the reliability is further improved. In addition, an adhesive in which a powder material such as glass, ceramic, or metal that inhibits the penetration of scale-degrading components such as moisture and gas may be used.

  In the embodiment, the scale substrate 12 is made of glass. However, the present invention is not limited to this. For example, in the case of a reflective photoelectric scale, the scale substrate 12 may be made of ceramic or metal.

  Further, the scale for the linear encoder for detecting the linear movement of the scale unit 14 has been described as an example. It may be a scale on which any scale part is formed. Further, not only the light transmission type photoelectric scale but also the reflection type as described above may be applied to various scales such as a capacitance type, a magnetic type, and an electromagnetic induction type. Absent.

DESCRIPTION OF SYMBOLS 10 ... Scale 12 ... Scale board 14 ... Scale part 16 ... Cover glass 18 ... Adhesive layer (agent)
20 ... Detector 30 ... Height defining part 32 ... Adhesive layer (agent)

Claims (4)

In the scale protection structure of the scale for detecting displacement, the scale part formed along the relative movement direction with the detector on the scale substrate is protected by the cover glass arranged on the upper surface side thereof.
The cover glass is supported on the scale substrate via a height defining portion disposed around the scale portion,
Said height defining portion, the lower surface of the cover glass, are pre deposited formed in the same thickness which is continuous in a pattern corresponding to the entire periphery of the scale part, and, abutting a lower end to the upper surface of the scale substrate And
Further, the scale protecting structure for a scale for detecting displacement, wherein the scale substrate and the cover glass are joined with an adhesive disposed around the height defining portion. The scale protection structure for a displacement detection scale according to claim 1, wherein the adhesive is disposed all around the height defining portion . The scale protection structure for a displacement detection scale according to claim 1, wherein the height defining portion and the scale portion are formed of the same kind of metal .   The scale-protecting structure for a displacement detection scale according to any one of claims 1 to 3, wherein the height defining portion is made of a metal made of chromium, copper, or aluminum.

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