JP2006329695A - Encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoder used under various environments and capable of conducting a stable detection operation all the time. <P>SOLUTION: This encoder 100 is provided with a detecting part 10 and an electrical part 60, and the electrical part 60 is provided with a light emitting element 62, an electric power source 64, a photoreception element 66, a detecting circuit 68 and the like. A dial plate 29 is stored in a case 12 of the detecting part 10. Light emitted from the light emitting element 62 is emitted to a slit of the dial plate 29 by a light irradiating optical fiber 50, and the light passed through the slit is guided to the photoreception element 66 by a photoreceiving optical fiber 52. The light irradiating optical fiber 50 and the photoreceiving optical fiber 52 are stored under a wound state in a fiber storage chamber 28 inside the case 12, in this side where the light irradiating optical fiber 50 and the photoreceiving optical fiber 52 reach the dial plate 29. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an encoder.

For example, a rotary encoder is used as an encoder that detects the amount of rotation of a motor drive shaft. This type of encoder includes a case and a scale plate, a light emitting diode, a light receiving element, and the like housed in the case. ing.
Then, the scale plate is formed with a plurality of slits and rotated in conjunction with the rotation of the drive shaft, the light emitting diodes are arranged facing the scale plate and irradiate the scale plate with light, and the light receiving element The light emitted from the light emitting diode and disposed through the scale plate is received and the amount of rotation is detected based on a detection signal output from the light receiving element (see Patent Document 1). ).

Japanese Patent Laid-Open No. 5-126599

In such a conventional encoder, a power supply provided outside the encoder case and the light emitting diode are connected by a power supply cable, and a signal processing circuit and a light receiving element provided outside are connected for detection signal transmission. Connected with a cable.
Therefore, since an electrical signal appears at the connection point between the power supply cable and the light emitting diode, or the connection point between the signal transmission cable and the light receiving element, it handles flammable paint or gasoline. There was a disadvantage in using in an explosion-proof environment.
In an environment where radiation is generated, the radiation damages the light emitting diode and the light receiving element, which is disadvantageous in ensuring durability.
Further, in an environment where a high voltage and a high magnetic field are generated, the voltage and the magnetic field affect the detection signal transmitted by the signal transmission cable, which is disadvantageous in reliably detecting the rotation amount.
Such a problem occurs not only in a rotary encoder but also in other encoders such as a linear encoder using the same detection principle.
The present invention has been made in view of such circumstances, and an object thereof is to provide an encoder that can be used in various environments and can always perform a stable detection operation.

  In order to achieve the above-described object, the encoder of the present invention has passed through the scale plate with a case, a scale plate, a light emitting element that emits light toward the scale plate, and light emitted from the light emitting element. An encoder including a light receiving element that receives light, wherein the light emitting element and the light receiving element are provided outside the case at a position away from the case, and guides light emitted from the light emitting element to the slit. A light irradiating optical fiber for irradiating the slit is provided, a light receiving optical fiber for guiding light that has passed through the slit to the light receiving element is provided, and the light irradiating optical fiber and the light receiving device are provided inside the case. A fiber storage chamber is provided that can be stored in a state where the optical fiber is wound. A part of the optical fiber for light irradiation and the optical fiber for light reception are part of the fiber. Their tips in a state of being housed in the server storage chamber is characterized in that it is arranged so as to face the scale plate.

According to the present invention, the light emitting element and the light receiving element are provided outside the case and away from the case, the light emitted from the light emitting element is irradiated to the slit by the optical fiber for light irradiation, and passed through the slit. The light is guided to the light receiving element by an optical fiber for receiving light.
Therefore, there are no light-emitting elements and light-receiving elements inside the case so that no electrical signal appears, so the case is exposed to an explosion-proof environment, an environment where radiation is generated, an environment where a high voltage or a high magnetic field is generated, etc. It is advantageous for performing stable detection operation at all times.
Moreover, since the optical fiber for light irradiation and the optical fiber for light reception are accommodated in the fiber housing chamber in the case before reaching the scale plate, the extra length processing of the optical fiber for light irradiation and the optical fiber for light reception is performed. It is easy to handle without breaking the optical fiber, which is advantageous for easy assembly work, and the location of the optical fiber protruding from the case can be easily changed and narrow This is advantageous in arranging the encoder in the space.

(First embodiment)
Next, embodiments of the present invention will be described with reference to the drawings.
1 is a cross-sectional view showing the configuration of the encoder according to the first embodiment, FIG. 2 is a view taken in the direction of the arrow A in FIG. 1, FIG. 3 is a view taken in the direction of the arrow B in FIG. FIG. 5 is a plan view of a fixed slit plate, and FIG. 6 is an explanatory view of the arrangement of optical fibers.
FIG. 7 is a block diagram illustrating a configuration of the encoder 100 according to the first embodiment.

As shown in FIG. 7, in the present embodiment, the encoder 100 is a rotary encoder that detects the amount of rotation of the motor 2.
The encoder 100 includes a detection unit 10 disposed in the vicinity of the motor 2 and an electrical unit 60 disposed at a location separated from the detection unit 10.
The electrical unit 60 is connected to the detection unit 10 via the light irradiation optical fiber 50 and the light receiving optical fiber 52, and includes a light emitting element 62, a power source 64, a light receiving element 66, a detection circuit 68, and the like.
The light emitting element 62 supplies light to the detection unit 10, and is configured by three light emitting diodes in the present embodiment.
The power source 64 supplies a driving current (power source) to the light emitting element 62 to emit light.
The light receiving element 66 receives light from the detection unit 10 and generates a detection signal. In the present embodiment, the light receiving element 66 includes three photodiodes.
The detection circuit 68 generates a digital signal corresponding to the rotation amount of the motor 2 based on the detection signal.

As shown in FIGS. 1 to 3, the detection unit 10 includes a case 12, and a rotation shaft 26 and a scale plate 29 are accommodated in the case 12.
The scale plate 29 includes a movable slit plate 30 and a fixed slit plate 32.
The case 12 includes a base 14, a tubular member 16, a partition member 18, and a cap 20.
The base 14 has a disk shape, and a center hole 1402 is formed through the center thereof. The base 14 is connected to a motor (not shown).
The cylindrical member 16 has a cylindrical shape with a smaller diameter than the base 14, and the rotation shaft 26 is rotatably supported by a central hole 1602 via a bearing 24. One end of the rotary shaft 26 is connected to the drive shaft of the motor 2 (FIG. 7) so as to be integrally rotatable, and a movable slit plate 30 is attached to the other end.
A fiber attitude changing chamber 27 is provided on the mating surface of the base 14 and the cylindrical member 16.
The partition wall member 18 has a disk shape that is slightly smaller in diameter than the cylindrical member 16 and smaller in thickness than the cylindrical member 16, and is attached to the opposite side of the cylindrical member 16 from the base 14.
Between the location where the tubular member 16 faces the partition member 18 and the location where the partition member 18 faces the tubular member 16, a scale plate housing chamber 22 communicating with the center hole 1602 and having an inner diameter larger than the center hole 1602 is formed. The movable slit plate 30 is accommodated in the scale plate accommodating chamber 22.
The cap 20 has a disk-shaped bottom wall 2002 and a cylindrical side wall 2004 erected from the periphery of the bottom wall 2002, and the tip of the side wall 2004 is attached to the outer periphery of the partition wall member 18. A fiber accommodating chamber 28 that can be accommodated in a state in which the optical fiber 50 for light irradiation and the optical fiber 52 for light reception are wound is formed between the inner side of the optical fiber and the partition member 18.
Therefore, the fiber posture change chamber 27 is provided in the case 12 at a location opposite to the location where the fiber storage chamber 28 of the scale plate storage chamber 22 is provided.
The cap 20 is provided with a fiber insertion port 2010 through which the light irradiating optical fiber 50 and the light receiving optical fiber 52 are inserted into the fiber housing chamber.
In this embodiment, three light irradiating optical fibers 50 and three light receiving optical fibers 52 are used, and these fibers are accommodated in one multi-core optical cable 54, and the multi-core optical cable 54 is inserted into the fiber. It is inserted through the mouth 2010.
The fiber insertion port 2010 is located with respect to the location of the cap 20 (bottom wall 2002) in the direction orthogonal to the surfaces of the movable slit plate 30 and the fixed slit plate 32 described later, and the surfaces of the movable slit plate 30 and the fixed slit plate 32. Are provided at at least two locations (side walls 2004) of the cap 20 in the parallel direction.
In the present embodiment, a sleeve 2012 is attached to the fiber insertion hole 2010 of the bottom wall 2002 of the cap 20, and the multi-core optical cable 54 is inserted into the sleeve 2012, and the fiber insertion port 2014 is inserted into the fiber insertion port via the O-ring 2016. It is attached to 2010.
The hole 2010 in which the sleeve 2012 is not mounted is closed with a removable cover 2020.

The movable slit plate 30 has a disk shape with an outer diameter that can be accommodated in the scale plate accommodating chamber 22, and as shown in FIG. 4, a plurality of first movable plates are arranged over the entire circumference in the circumferential direction of the rotation center of the movable slit plate 30. A slit 3002 is formed.
In addition, a plurality of second movable slits 3004 are formed on a part of the circumference having a different radius from those of the first movable slits 3002.

A fixed slit plate 32 is attached to the partition member 18 so as to face a part of the movable slit plate 30.
The fixed slit plate 32 has a disk shape, is accommodated in the scale plate accommodating chamber 22, and is disposed so as to overlap the movable slit plate 30.
As shown in FIG. 5, at a position where the fixed slit plate 32 faces the first movable slit 3002 of the movable slit plate 30, a plurality of first fixed slits 3202 </ b> A are provided in a part of the circumferential direction of the movable slit plate 30. A plurality of second fixed slits 3202B are formed at intervals in the circumferential direction.
In addition, a third fixed slit 3204 is formed in a part of the circumferential direction where the fixed slit plate 32 faces the second movable slit 3004 of the movable slit plate 30.

As shown in FIGS. 2 and 3, the tubular member 16 and the partition member 18 are formed with three insertion holes 29 that allow the fiber accommodation chamber 28 and the fiber posture change chamber 27 to communicate with each other.
As shown in FIGS. 2 and 6, the cylindrical member 16 has three attachment holes 1610 </ b> A, 1610 </ b> B, and 1612 for the light irradiation fiber 50 communicating with the fiber posture changing chamber 27 and the scale plate housing chamber 22. Has been. The three attachment holes 1610A, 1610B, and 1612 are provided at locations facing the first fixed slit 3202A, the second fixed slit 3202B, and the third fixed slit 3204.
As shown in FIGS. 3 and 6, the partition wall member 18 is formed with three mounting holes 1810A, 1810B, and 1812 for the light receiving optical fiber 52 that communicates the fiber housing chamber 28 and the scale plate housing chamber. Yes. The three attachment holes 1810A, 1810B, and 1812 are provided at locations facing the plurality of first fixed slits 3202A, the plurality of second fixed slits 3202B, and the third fixed slit 3204.

As described above, in the present embodiment, the detection unit 10 and the electrical component 60 are connected by one multi-core optical cable 54, and the three light irradiation optical fibers 50 and the three light reception optical fibers 52 are tubular. Is housed in the covering member 5402.
Each of the light irradiation optical fiber 50 and the light receiving optical fiber 52 has a core positioned at the center and a clad covering the core, and the outer side of the clad is covered with a sheath (coating) made of a synthetic resin material or the like. Yes.
In the present embodiment, the core of the light receiving optical fiber 52 is formed with a larger cross section than the core of the light irradiating optical fiber 50.
The base end of each light irradiation optical fiber 50 is connected to each light emitting diode of the light emitting element 62.
The base end of each light receiving optical fiber 52 is connected to each photodiode of the light receiving element 66.

The multi-core optical cable 54 inserted into the fiber housing chamber 28 from the fiber insertion port 2010 is exposed to the three light irradiation optical fibers 50 and the three light receiving optical fibers 52 from the coating member 5402 in the fiber housing chamber 28. The ferrule 53 is attached to the tip of each light irradiation optical fiber 50 and each light receiving optical fiber 52.
The three optical fibers 50 for light irradiation pass straight through the fiber insertion port 2010 toward the fiber posture changing chamber 27 to reach the fiber posture changing chamber 27 and bend in the fiber posture changing chamber 27. The direction is changed by 180 degrees, and the ferrule 53 is inserted into the attachment hole 1610A together with the collimator lens 5004. The collimator lens 5004 and the ferrule 53 are attached to the attachment hole 1610A using an adhesive, for example.
Further, the ferrule 53 at the tip of the three light receiving optical fibers 52 is inserted into the attachment holes 1810A, 1810B, and 1812 together with the collimator lens 5204, respectively. The collimator lens 5204 and the ferrule 53 are attached to the attachment holes using an adhesive, for example. It is attached to 1810A, 1810B, 1812.

Next, the operation will be described.
When a current is supplied from the power source 64 to the light emitting element 62 and each of the light emitting diodes emits light, the light is transmitted to the three light emitting optical fibers 50 and emitted from the ferrule 53 at the tip of the three light emitting optical fibers 50. Then, the collimator lens 5004 becomes parallel light and irradiates the movable slit plate 30 respectively.
That is, of the three light irradiation optical fibers 50, the light irradiated from one light irradiation optical fiber 50 through the ferrule 53 and the collimator lens 5004 is the first movable slit 3002 of the movable slit plate 30. , Passing through the first fixed slit 3202A of the fixed slit plate 32, being guided to one of the three light receiving optical fibers 52 through the collimator lens 5204 and the ferrule 53, A detection signal A (FIG. 7) is generated by the photodiode of the light receiving element 66 via the light receiving optical fiber 52.
Of the three light irradiation optical fibers 50, the light irradiated from the other light irradiation optical fiber 50 through the ferrule 53 and the collimator lens 5004 is the first movable slit of the movable slit plate 30. 3002 passes through the second fixed slit 3202B of the fixed slit plate 32, and is guided to another one of the three light receiving optical fibers 52 through the collimator lens 5204 and the ferrule 53, and this light receiving light. Light is received by the photodiode of the light receiving element 66 through the fiber 52, and a detection signal B (FIG. 7) is generated.
That is, as the first movable slit 3002 moves with respect to the first and second fixed slits 3202A and 3202B with the rotation of the rotation shaft 26, the optical path is blocked for each pitch of the slits. A proportional number of times of light and dark occur. Therefore, the detection signals A and B are signals that increase and decrease repeatedly corresponding to this light and dark.
The detection circuit 68 generates a digital signal corresponding to the rotation amount of the motor 2 based on the two detection signals A and B that increase and decrease in this way.
The rotation amount data is obtained by supplying the digital signal to a conventionally known counter circuit or the like.
Of the three light irradiation optical fibers 50, the light irradiated from the remaining one light irradiation optical fiber 50 via the ferrule 53 and the collimator lens 5004 is the second movable slit 30. The light passes through the slit 3004 and the third fixed slit 3204 of the fixed slit plate 32 and is guided to the remaining one of the three light receiving optical fibers 52. Light is received by the 66 photodiodes and a detection signal C (FIG. 7) is generated.
That is, as the rotation shaft 26 rotates, the second movable slit 3004 matches the third fixed slit 3204, so that an optical path is formed, and light is transmitted every rotation of the rotation shaft 26. Therefore, the detection signal C is a signal generated corresponding to the transmission of this light.
The detection circuit 68 detects the reference position (absolute position) of the rotation angle of the movable slit plate 30 with respect to the fixed slit plate 32 based on such a detection signal C.

According to the encoder 100 of the present embodiment, the light emitting element 62 and the light receiving element 66 are provided outside the case 12 at a location away from the case 12, and the light emitted from the light emitting element 62 is transmitted by the light irradiation optical fiber 50. The light that was irradiated to the slit and passed through the slit was guided to the light receiving element 66 by the light receiving optical fiber 52.
Therefore, since only the movable slit plate 30 and the fixed slit plate 32 are provided inside the case 12, an electrical signal does not appear inside the case 12, so that the case 12 is installed in an explosion-proof environment, and If the light emitting element 62 and the light receiving element 66 are installed in an environment other than the explosion-proof environment, the encoder 100 can be used in the explosion-proof environment.
If the case 12 containing only the movable slit plate 30 and the fixed slit plate 32 is installed in an environment where radiation is generated, and the light emitting element 62 and the light receiving element 66 are installed in an environment where no radiation is generated, Radiation does not damage the light emitting diode and the light receiving element, which is advantageous in ensuring the durability of the encoder 100.
Further, the case 12 in which only the movable slit plate 30 and the fixed slit plate 32 are accommodated is installed in an environment where a high voltage and a high magnetic field are generated, and the light emitting element 62 and the light receiving element 66 generate a high voltage and a high magnetic field. If installed in an environment that does not, the voltage and magnetic field will not affect the detection signal output from the light receiving element 66, so that the amount of rotation can be reliably detected and stable detection operation can be performed. It will be advantageous.

In the present embodiment, the light irradiation optical fiber 50 and the light receiving optical fiber 52 are wound before the light irradiation optical fiber 50 and the light receiving optical fiber 52 reach the scale plate 29. Since the optical fiber 50 for light irradiation and the optical fiber 52 for light reception are accommodated in the attachment holes 1602A, 1602B, 1604, 1802A, 1802B, 1804 because they are accommodated in the fiber accommodating chamber 28 in the case 12. Extra length processing (length adjustment, etc.) can be easily performed, and the optical fiber can be easily routed without breaking, which is advantageous for easy assembly work.
Further, before the light irradiating optical fiber 50 and the light receiving optical fiber 52 reach the scale plate 29, the light irradiating optical fiber 50 and the light receiving optical fiber 52 are wound and accommodated in the case 12. Since it is accommodated in the chamber 28, the fiber insertion port 2010 to the case 12 of the multi-core optical cable 54 can be easily changed without breaking the optical fiber, depending on the space where the encoder is arranged, that is, The location of the multi-core optical cable 54 protruding from the case 12 can be easily changed, which is advantageous in arranging the encoder 100 in a narrow space.
In the present embodiment, since a plurality of fiber insertion ports 2010 are provided at different locations of the cap 20, the location of the multi-core optical cable 54 protruding from the case 12 can be changed more easily, and the encoder 100 is arranged in a narrow space. This is even more advantageous.

Further, after the light irradiating optical fiber 50 is routed from the fiber housing chamber 28 to the fiber posture changing chamber 27, the light irradiating optical fiber 50 is disposed so as to face the scale plate 29, and an optical fiber having a small core cross section is disposed on the light irradiating optical fiber 50. Since it is used, the optical fiber 50 for irradiating light can be easily routed without damaging it, which is advantageous in simplifying the assembly work.
Further, since an optical fiber having a larger core cross section than the light irradiation optical fiber 50 is used as the light receiving optical fiber 52, the light emitted from the collimator lens 5004 of the light irradiation optical fiber 50 is used as the light receiving optical fiber. The 52 collimator lenses 5204 are advantageous in receiving light efficiently.
Further, since the light receiving optical fiber 52 having a large core cross section may be directly inserted into the mounting holes 1802A, 1802B, and 1804 from the fiber accommodating chamber 28, the light receiving optical fiber 52 can be easily handled and assembled. This is advantageous for simple execution.

In this embodiment, since the core of the light receiving optical fiber 52 is formed with a larger cross section than the core of the light irradiating optical fiber 50, the light is emitted from the collimator lens 5004 of the light irradiating optical fiber 50. This is advantageous in efficiently receiving light by the collimator lens 5204 of the optical fiber 52 for receiving light.
Therefore, the optical performance of the collimator lenses 5004 and 5204 is relatively low compared to the case where the core of the light receiving optical fiber 52 and the core of the light irradiating optical fiber 50 are formed with the same cross section. There is no problem even if one is used, which is advantageous in securing a degree of freedom in design and reducing costs.

A connector may be provided at the fiber insertion port 2010 of the case 12 so that the detection unit 10 and the electrical unit 60 can be separated.
In this case, the light irradiating optical fiber 50 is wound in the fiber storage chamber 28 and has a first portion whose tip faces the scale plate 29 and a second portion connected to the light emitting element 62 and reaching the case 12. Has a part.
The light receiving optical fiber 52 has a first portion wound in the fiber storage chamber 28 and having a tip thereof facing the scale plate 29 and a second portion connected to the light receiving element 66 and reaching the case 12. Yes.
Then, a connector is attached to the fiber insertion port 2010, and the base end of the first portion of the light irradiation optical fiber 50 and the base end of the first portion of the light receiving optical fiber 52 are connected to the connector, The distal end of the second portion of the light irradiating optical fiber 50 and the distal end of the second portion of the light receiving optical fiber 52 are connected to a connector detachable from the connector.

In the present embodiment, the case where the encoder 100 is a rotary encoder has been described. However, it goes without saying that the present invention can also be applied to a linear encoder.
In this case, the scale plate 29 includes a main scale formed with a large number of slits and extending linearly, and a fixed slit plate provided with a plurality of slits.
The case 12 is provided so as to be movable along the longitudinal direction of the main scale, the fixed slit plate is fixed in the case 12, and other configurations are the same as those of the rotary encoder.

It is sectional drawing which shows the structure of the encoder 100 of 1st Embodiment. It is A arrow directional view of FIG. It is a B arrow line view of FIG. It is a top view of a movable slit board. It is a top view of a fixed slit board. It is arrangement | positioning explanatory drawing of an optical fiber. It is a block diagram which shows the structure of the encoder 100 of 1st Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Case, 28 ... Fiber storage chamber, 29 ... Scale plate, 50 ... Optical fiber for light irradiation, 52 ... Optical fiber for light reception, 62 ... Light emitting element, 66 ... Light receiving element, 100 ... ... encoder.

Claims (9)

Case and
A dial plate,
A light-emitting element that emits light toward the scale plate;
A light-receiving element that receives light that has passed through the scale plate with light emitted from the light-emitting element;
The light emitting element and the light receiving element are provided outside the case and away from the case,
A light irradiating optical fiber is provided for guiding the light emitted from the light emitting element to the slit and irradiating the slit;
A light receiving optical fiber for guiding the light passing through the slit to the light receiving element is provided;
Inside the case, a fiber storage chamber is provided that can be stored in a state where the optical fiber for light irradiation and the optical fiber for light reception are wound,
The optical fiber for light irradiation and the optical fiber for light reception are arranged with their tips facing the scale plate in a state where a part of them is stored in the fiber storage chamber,
An encoder characterized by that.   The light irradiating optical fiber is wound in the fiber storage chamber, and then is bent in the case to reach a location on the opposite side of the scale plate from the location where the fiber storage chamber is provided. The optical fiber for receiving light is wound in the fiber storage chamber and then extends toward the scale plate, and the tip of the optical fiber for reception is placed on the scale plate. The encoder according to claim 1, wherein the encoder is arranged so as to face.   The scale plate is disposed in a scale plate housing chamber of the case, and a fiber attitude that changes the direction of the optical fiber to a location on the opposite side of the scale plate housing chamber from the location where the fiber housing chamber is provided. The encoder according to claim 2, wherein a change chamber is provided, and the bending of the optical fiber for light irradiation is performed in the fiber posture change chamber.   The optical fiber for light irradiation and the optical fiber for light reception each have a core, and the core of the optical fiber for light reception is formed with a larger cross section than the core of the optical fiber for light irradiation. The encoder according to any one of Items 1 to 3.   The encoder is a rotary encoder, and the scale plate includes a fixed slit plate fixed in the case and provided with a plurality of slits, and a plurality of slits arranged on the fixed slit plate in the case. The encoder according to any one of claims 1 to 4, further comprising a movable slit plate that is provided and rotated.   The encoder is a linear encoder, and the scale plate includes a main scale formed with a large number of slits and extending linearly, and a fixed slit plate provided with a plurality of slits, and the case includes the main scale. The encoder according to any one of claims 1 to 4, wherein the encoder is provided so as to be movable along a longitudinal direction, and the fixed slit plate is fixed in the case.   7. The encoder according to claim 1, wherein tips of the light irradiation optical fiber and the light receiving optical fiber face the scale plate via a collimator lens, respectively.   The case is provided with a fiber insertion port through which the light irradiating optical fiber and the light receiving optical fiber are inserted into the fiber housing chamber, and the fiber insertion port is in the direction orthogonal to the surface of the scale plate. The encoder according to any one of claims 1 to 7, wherein the encoder is provided at at least two of the case part and the case part in a direction parallel to the surface of the scale plate.   The case is provided with a fiber insertion port for communicating the outside of the case with the fiber housing chamber, and the light irradiating optical fiber is housed in the fiber housing chamber, and a tip thereof faces the scale plate. And a second portion connected to the light emitting element and reaching the case, the light receiving optical fiber being housed in the fiber housing chamber, and a first portion having a tip thereof facing the scale plate; A second portion connected to the light receiving element to reach the case, a connector is attached to the fiber insertion port, a proximal end of the first portion of the optical fiber for light irradiation, and the light receiving The proximal end of the first portion of the optical fiber for use is connected to the connector, and the connector is provided at the distal end of the second portion of the optical fiber for light irradiation and the distal end of the second portion of the optical fiber for light reception. Removable connector Any one encoder according to claim 1 to 8, characterized in that it is connected.

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