JPH09196703A - Optical encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent mixing of lights of a plurality of phases passing through a slit. SOLUTION: A first reflection mirror 34 and a second reflection mirror 35 of an optical guide of a main body 30 of a fixed part made of transparent resin and having a conical coaxial reflecting face are provided with L-shaped grooves or projecting parts 34L, 35L annularly in the whole periphery as reflecting light-erasing parts. More specifically, the L-shaped groove or projecting part 34L, 35L having a perpendicular face to an entering detection light is set at a position opposite to a slit interval of a boundary of signal detection lights adjacent to each other in a radial direction. The reflecting light-erasing parts may be arranged at the side of a main body 20 of a rotary part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical encoder for detecting a plurality of signals such as speed, angle and position of a rotary shaft of a high speed rotating body such as a motor.

[0002]

2. Description of the Related Art An optical encoder converts a parallel light beam projected from a light emitting source into an intermittent signal by passing through both slits of a rotating disk and a fixed disk, and the intermittent signal of this light is received by a light receiving element. The light is received and converted into an electric signal to measure the angle and speed of the rotating body.

For example, according to Japanese Utility Model Publication No. 49-109567 and Japanese Utility Model Publication No. 55-148642,
As shown in FIG. 9, a light emitting source 40 for projecting the light emitted from the light emitting element as a parallel light flux, and a plurality of radial slits 22 fixed to the rotation axis of the rotating body 100 are arranged at equal intervals of a pitch p toward the peripheral portion. Disk-shaped rotating part 2 arranged in a ring
0, a disk-shaped fixed part 30 provided in parallel with the rotating part 20 and having a plurality of radial slits 32 annularly arranged near the peripheral part, and both slits of the rotating disk and the fixed disk. And a light receiving element 50 for receiving light.
The parallel light beam projected from the laser beam passes through both slits of the rotating disk and the fixed disk and is converted into an intermittent signal. The intermittent signal of this light is received by the light receiving element 50 and converted into an electric signal to determine the angle of the rotating body. Or to measure the speed, etc., light is evenly and vertically emitted to a plurality of slits in the circumferential direction and the radial direction provided near the peripheral portion of the rotating disk and the fixed disk, Light receiving section 50 that collects light that has passed through the slit
The rotary unit 20 of the transparent light diffusion guide that radially diffuses the light flux incident from the light source unit 40 and projects the light flux perpendicularly to the disc over the entire outer peripheral portion, the rotary slit 22, and the fixed slit 32. It is disclosed that a fixed portion 30 of a transparent light collecting guide that collects the light flux that has passed through and is interrupted from the entire outer peripheral portion and projects the light flux onto the light receiving portion 50 is provided.

The light projected from the light source in parallel to the rotation axis of the rotating body 100 is reflected by the first annular reflecting mirror 24 of the rotating body 20 of the light diffusion guide and is perpendicular to the rotating axis 100 so as to move away from the axis. Of the rotary slit disk 22, which is radially diffused in the plane of the rotary slit 20, passes through the inside of the transparent rotating portion 20, is reflected by the second annular reflecting mirror 25, is parallel to the axis, and is cylindrical. To the slit 22. And
The light passing through the slit 32 of the fixed slit disc 31 is
The second annular reflecting mirror 35 of the fixed portion 30 causes the rotating shaft 100 to rotate.
It is reflected in a plane shape at right angles to and toward the axis, passes through the inside of the transparent fixed portion 30, is condensed by the first annular reflecting mirror 34 in parallel with the axis, and is rotated in the rotation axis direction. The light is guided toward the light receiving element 50 provided.

Further, as shown in FIG. 10, the optical encoder for detecting a plurality of signals such as the speed, the angle and the position as described above is a signal to be detected by the slit 32 of the fixed slit disk 31. It is divided into a plurality of stages in the radial direction such as the same number as two, that is, 32A and 32B in this example, and the phases are also shifted in the rotation direction by ¼p pitch.

[0006]

However, in the conventional optical encoder as described above, the error of the working accuracy of the annular reflecting surface of the transparent body which constitutes the light diffusion guide of the rotating part and the light collecting guide of the fixed part is reduced. Therefore, as shown in FIG. 11, a plurality of radial detection lights La and Lb having different phases and having passed through the slits due to impaired parallelism of the respective light fluxes have a boundary surface 33 ′ between them.
However, there is a problem in that the light receiving elements cannot accurately detect signals because they are mixed with each other.

Further, when the detection lights having different phases are mixed with each other, not only the phases of the respective detection lights are deviated but also the outputs cancel each other, resulting in a small detection signal.

An object of the present invention is to solve the above-mentioned problems and to provide a compact optical encoder capable of preventing a plurality of detected light beams having different phases from being mixed with each other.

[0009]

An optical encoder according to the present invention is provided with at least one reflecting mirror surface of a first reflecting mirror and a second reflecting mirror of each of a light guide on a rotating portion side and a light guide on a fixed portion side. Further, there are provided N-1 N-shaped annular reflected light erasing portions each having a surface perpendicular to the incident light at the position corresponding to each boundary of the optical signals of the plurality of phases N.

Further, at least one of the light guides on the rotating portion side and the fixed portion side is constituted by a coaxial hollow truncated cone-shaped transparent member having an inclination angle of 45 degrees with respect to the axis.
It is desirable to provide the reflecting mirror and the second reflecting mirror on the inner conical surface and the outer conical surface of the truncated cone-shaped transparent member, respectively.

Further, it is desirable that a light guide formed of a transparent member also serves as a constituent member of the rotating portion or the fixed portion.

Further, it is desirable that the constituent member of the rotating portion has a hub function for connecting the rotating shaft and the rotating portion.

Further, it is preferable that the component of the fixing part has a function of positioning the light emitting element of the light source part, and the positioning central axes of the fixing part and the light source part are on the same axis as the rotation central axis.

Further, it is desirable that the convex lens function for converting the light emitted from the light emitting element into a parallel light flux is constituted by a constituent member of the fixed portion.

Further, it is desirable to dispose a signal conversion device for amplifying and waveform-shaping the signal detected by the photoelectric conversion element of the light receiving portion on the side surface of the fixed portion facing the rotating portion side.

Further, it is desirable that the light source section and the light receiving section are arranged on the front and back sides of the substrate of the signal conversion device, and the light reflection direction of the light guide is set in accordance with this arrangement.

Further, it is preferable that a peripheral portion of the fixed portion is extended to the rotary portion side in a cylindrical shape having a predetermined length to form a labyrinth function and a gap adjusting function between the rotary portion and the fixed portion.

Due to the vertical surface of the L-shaped annular reflected light erasing portion, the light incident on the positions corresponding to the respective boundaries of the adjacent light flux signals is totally reflected or goes straight in the incident direction to the right angle direction. The reflected light is erased.

In this operation, each light guide is composed of a coaxial hollow hollow truncated cone-shaped transparent member, and a first reflecting mirror and a second reflecting mirror are provided on the inner conical surface and the outer conical surface of the transparent member, respectively. This is also effective in the case, and moreover, by constructing in this way, the work can be facilitated and the device can be miniaturized.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The optical encoder of the present invention is an optical encoder for detecting signals of a plurality of phases such as a rotation speed, a rotation direction and an angle of a rotating body such as a motor, for example,
A plurality of rotating bodies (here, 2
Optical encoder 11 for detecting the signal of
2 of the second conical reflecting mirrors 35A and 35B of the fixed part main body 30
An L-shape having a surface perpendicular to the detection light which passes through the two slits 32A and 32B of the fixed slit disk 31 and is incident as a reflected light erasing portion at a position (center portion) facing the boundary between the slits of the step. -Shaped groove portion 35L is provided, and the first conical reflecting mirror 3 facing the groove portion 35L of the second conical reflecting mirror 35 is further provided.
A groove 34L having a surface perpendicular to the detected light flux incident from the second conical reflecting mirror is also provided at the corresponding position of 4 as a similar reflected light erasing portion.

As shown in the cross-sectional view of FIG. 2, the structure of the reflected light erasing portions 34L and 35L is such that one L-shaped surface, whose two surfaces are orthogonal to each other, is perpendicular to the incident light beam and is a conical reflecting surface. It may be provided in an annular shape on the upper side, and a case where it is provided as a groove type on the conical reflecting mirror is shown in (A), and a case where it is provided as a protrusion is shown in (B). Both have the same effect and effect,
Depending on the location, you can select the one that is easier to work with.
A required number of such groove-type or projection-type reflected light erasing portions are annularly provided in the boundary area of adjacent signals over the entire circumference on the conical reflecting surface.

These two grooves or protrusions 34L, 35
By providing L, the adjacent detection lights La and Lb that pass through the two slits 32A and 32B of the fixed slit disk 31 and are incident are at right angles from the conical reflecting mirrors 35 and 34 at the boundary portion 33 thereof. Not reflected, the groove portions 35L, 34
It goes straight to L and is reflected so that it penetrates or returns to the incident direction,
It is possible to prevent the detection lights of the respective stages from mixing together.

[0023]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a first embodiment of the optical encoder of the present invention.

The optical encoder 11 of the present embodiment has a rotary body 20 having a transparent resin optical guide fixed to a rotary shaft of the rotary body 100 to be measured by a hub 23 as a constituent member.
A light source section 40 including a lens 42 for collimating the light emitted from the light emitting diode 41 into a parallel light flux, the slits 22,
A light receiving unit 50 including two sets of photodiodes 51A and 51B for detecting the two sets of optical signals La and Lb that have passed through 32A and 32B and converting them into electrical signals, and a light source unit 40.
And a light receiving portion 50, and a fixing portion main body 30 having a light guide made of transparent resin as a constituent member. As shown in FIG. 10, an opaque rotating slit disk 21 of an opaque body in which rotating slits 22 are radially arranged at equal intervals of a pitch P over the entire circumference is attached to the rotating portion main body 20. Further, the fixed slit disk 3 attached to the fixed portion main body 30.
1, a fixed slit 32A divided into two equal parts in the radial direction,
32B are arranged radially at equal intervals of pitch P over the entire circumference, corresponding to the rotary slits 22 of the rotary slit disk 21. Further, the light guide portions of the rotary unit main body 20 and the fixed unit main body 30 are opposed to each other in a direction perpendicular to a conical reflection surface having an angle of 45 degrees with respect to the rotation axis of the rotating body 100. However, each conical reflecting surface has a first reflecting mirror 24, 34 and a second reflecting mirror 25, 35 whose mirror surface precision is finished. Although the conversion device 60 is shown in FIG. 1 as being attached to the fixed part body 30, it may be provided separately from the main body of the optical encoder.

Although the above is the same structure as the conventional optical encoder, the optical encoder 11 of the present embodiment further includes the fixed slit disk 3 as shown in the sectional view of FIG.
The first reflecting mirror 35 and the first reflecting mirror 35 on which the light flux after passing through
At the position corresponding to the boundary surface 33 between the two signals A and B to be detected on the reflecting mirror 34, one L-shaped groove portion 35L is formed so that one surface thereof is perpendicular to the incident light. , 3
By providing 4L all over the circumference, the optical signal incident on this groove is transmitted or reflected in a direction different from the reflection direction from the adjacent reflection surface, and the adjacent optical signal L
It prevents the a and Lb from being mixed together.

The light emitted from the light emitting diode 41 of the light source section 40 passes through the convex lens 42 to become a parallel light flux L1 and enters the first reflecting mirror 24 of the rotating section body 20. First
In the reflecting mirror 24, the incident parallel light flux L1 is radially reflected by the conical reflecting surface of 45 degrees in the direction perpendicular to the rotation axis over the entire circumference, and is incident on the second reflecting mirror 25 as L2. This incident light L2 is reflected at a right angle by the 45-degree conical reflecting surface of the second reflecting mirror 25, and the rotating body 1
00 is parallel to the axis of rotation, and the rotary slit disk 21
A cylindrical light beam L3 having the same diameter as that of the light beam is incident on the rotary slit disk 21.

Rotating slit 22 of rotating slit disk 21
The light beam L3 that has passed through is projected onto a fixed slit disk 31 provided opposite to the other surface of the rotary slit disk 21. In the fixed slit disc 31, as shown in FIG.
Fixed slits 32A, 32 on the two-tiered track in the radial direction
B is provided at the same pitch P as the rotary slit 22 over the entire circumference. However, the fixed slit 32A and the fixed slit 32B are shifted in pitch in the circumferential direction by an angle of 1 / 4P.

Light flux L projected on the fixed slit disk 31
3 is split into two intermittent light beams La and Lb by the fixed slits 32A and 32B, and is incident on the second reflecting mirror 35 of the fixed portion main body 30 having an L-shaped groove portion 35L in the center as shown in FIG. To do. The light fluxes La and Lb that are incident on the 45-degree conical reflecting surface of the second reflecting mirror 35 and are parallel to the axis are light fluxes L4a and L4b that are reflected at right angles and travel in the axis direction. However, the light flux La or Lb incident on the central groove portion 35L strikes a surface perpendicular to one of the L-shaped incident light rays and is transmitted, or is reflected in the opposite incident direction and is not reflected in the axial direction. . That is, the light flux spread in the boundary area between the two light fluxes La and Lb is prevented from being reflected in the axial direction, and the two light fluxes La and Lb can be separated from each other and prevented from being mixed with each other. it can.

Two luminous fluxes L4a and L4b directed in the axial direction
Is reflected at a right angle by the first reflecting mirror 34 of the fixed part main body 30 and becomes a light beam parallel to the rotation axis and enters the photodiodes 51A and 51B of the light receiving part 50, respectively. Here again, the L-shaped groove portion 3 provided in the center of the first reflecting mirror 34
By 4L, as in the second reflecting mirror 35, 2
The reflection of the light beam spread in the boundary area between the two light beams L4a and L4b toward the light receiving section 50 is blocked, and the two light beams L4a and L4b are blocked.
Can be separated into pure optical signals and sent to the respective photodiodes.

As shown in FIG. 6, the photodiode 51 of the light receiving section 50 is such that two concentric annular photodiode elements 51A and 51B are arranged on the same photodiode 51, and two photodiodes are provided as a light receiving element substrate 53. The electric signals A and B having different phases are obtained.

In this embodiment, the number N of signals to be detected has been described as 2. However, in the case of detecting 3 or more signals, the number N of radial arrangement of concentric fixed slits and photodiode elements is increased. It is obvious that a total of N-1 L-shaped groove portions for preventing reflection may be provided at positions corresponding to the boundaries of the steps of the conical reflecting surface.

Further, in this embodiment, since the hub 23 of the rotating portion main body 20, the first reflecting mirror 24, and the second reflecting mirror 25 are integrally molded by the transparent resin mold, each portion is formed by the same rotating shaft. It can be placed on top accurately. Similarly,
The first reflecting mirror 34 and the second reflecting mirror 35 of the fixed part main body 30 are integrally molded by a transparent resin mold, and the light source part 40
By arranging the light receiving unit 50 and the light receiving unit 50 at the center of the rotation axis, the light source unit 40 and the light receiving unit 50 can be easily positioned.

FIG. 4 is a sectional view of the optical encoder 12 according to the second embodiment. It shows the light source section 40 and the light receiving section 50 of the first embodiment.
The structure is such that and are replaced. In this case as well, by integrally molding the fixing portion main body 30 with a resin mold, the resin mold can also serve as a positioning component, and the light source portion 40 and the light receiving portion 50 can be easily arranged at the center of the rotation axis. You can In addition, the light source unit 40 and the light receiving unit 5
Since 0 is exchanged, the directions of the luminous fluxes L1 to L4 are reversed, and the L-shaped groove portions 24L and 25L for erasing the reflected light.
However, the optical signals modulated by the slits 32 and 22 are provided on the first and second reflecting mirrors 24 and 25 on the rotating unit main body 20 side before entering the light receiving unit 50. However, its action is
Similar to the embodiment, the two luminous fluxes L4a and L4b are separated into pure optical signals, and each photodiode 51 is separated.
Can be sent to A, 51B. Further, in this example, the optical encoder is further miniaturized by arranging the conversion device 60 for converting the optical signal detected by the photodiodes 51A and 51B into an electric pulse signal in the space on the fixed part body 30 side. Is.

3A and 3B are cross-sectional views showing an application example of the structure of the convex lens 42. FIG. 3A is one integrally molded with the constituent member of the fixed part main body 30, and FIG. 3B is a structural member of the rotary part main body 20. It is integrally molded. As shown, the convex lens 42
By configuring the stationary part or the rotating part with the transparent resin mold, the number of parts and the number of assembling steps can be reduced.

FIG. 5 shows the rotary body 20 and the stationary body 30.
In an enlarged cross-sectional view of both slit facing portions, a part of the peripheral circumference of the fixed resin body 30 made of a transparent resin mold is extended to the rotating portion side in a cylindrical shape having a length l (el) to collect dust from the outside. Has a labyrinth function 70 for preventing invasion of the like, and the reference surface 20A of the distal end of the cylindrical portion and the hub 23 of the rotating portion main body 20.
Are made to be the same, and a gap G adjusting function between the rotary slit disc 21 and the fixed slit disc 31 is provided. That is, by extending the constituent members of the fixed portion main body 30 into a cylindrical shape like a cover that covers the rotary portion main body 20,
It constitutes the labyrinth part. This structure prevents external dust from entering the inside of the optical encoder,
Improves reliability. Further, in order to obtain an appropriate gap between the slits, the tip end surface of the cover is attached to the hub 23 of the rotating unit.
If the length l (L) of the cylindrical cover portion is determined so that it is on the same plane as the reference plane, the tip end surface of the cover is made flush with this reference plane with a jig when setting the gap. If matched, the aptitude gap can be set with one touch.

FIGS. 7 and 8 show an application modification of the arrangement of the conversion device 60, in which the light source unit 40 and the light receiving unit 50 are arranged on the front and back sides of one conversion device substrate 61, and light is received from the light source unit 40. The first reflecting mirrors 34 and 24 of the fixed portion or the rotating portion are configured so that the reflection direction of the detection light to the portion 50 is changed by 180 degrees. In this structure, since the light source unit 40, the light receiving unit 50, and the conversion device 60 are integrated on one substrate 61, the number of parts can be reduced, the device can be downsized, and the cost can be reduced. There is.

[0038]

As described above, according to the present invention, at least one reflecting mirror surface of each of the optical guides on the rotating portion side and the fixed portion side corresponds to each boundary that is adjacent in the radial direction of a plurality of N optical signals. By providing N-1 N-shaped annular reflected light erasing sections each having a surface perpendicular to the incident light from the position, the detection light entering the light receiving section from the boundary of the adjacent optical signals can be detected. There is an effect that erasing can be performed and the detection lights of a plurality of signals can be separated respectively to detect pure signals individually.

Further, at least one of the rotating portion side and the fixed portion side is constituted by a transparent member of a light guide in the shape of a conical hollow circular truncated cone, and the first reflecting mirror and the second reflecting mirror are respectively formed on outer cones of the transparent member. By providing the surface and the inner conical surface, it is easy to make the reflecting surfaces of the first reflecting mirror and the second reflecting mirror face each other, and the effect of the reflected light erasing portion can be maintained for a long time.

Further, since the light guide formed of a transparent member also serves as a constituent member of the rotating portion or the fixed portion, and the constituent member of the rotating portion has a hub function for connecting the rotating shaft and the rotating portion, two conical reflections are formed. The surface, hub, etc. can be integrated and can be manufactured by resin molding, respectively, which has the effect of reducing the size and cost of the optical encoder.

Further, by arranging the light emitting element of the light source unit on the same axis as the rotation center axis, the light emitting element can be downsized,
This has the effect of reducing manufacturing costs.

Further, a signal conversion device for amplifying and waveform-shaping a signal detected by the photoelectric conversion element of the light receiving part is arranged on the side surface of the fixed part facing the rotating part side, and the light source part and the light receiving part of the signal conversion device. By arranging them on the front and back of the substrate and setting the light reflection direction of the light guide in accordance with this arrangement, the positioning parts for the light source part and the light receiving part can be integrated, and each part can be arranged accurately.

Further, the peripheral portion of the fixed portion is extended to the rotating portion side in a cylindrical shape having a predetermined length to form a labyrinth function and a gap adjusting function between the rotating portion and the fixed portion.
This has the effect of simplifying the gap setting of the optical encoder and improving reliability.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical encoder 11 according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a reflected light eraser 35L. (A) Groove type reflected light erasing section (B) Protrusion type reflected light erasing section

FIG. 3 is a sectional view showing a structure of a convex lens 42. (A) One integrally formed with the constituent member of the fixed portion main body 30 (B) One integrally formed with the constituent member of the rotating portion main body 20

FIG. 4 is an optical encoder 12 according to a second embodiment of the present invention.
FIG.

FIG. 5 is a partially enlarged sectional view of an embodiment of the present invention.

FIG. 6 is an enlarged view of a light receiving unit 50.

FIG. 7 is an optical encoder 13 according to a third embodiment of the present invention.
FIG.

FIG. 8 is an optical encoder 14 according to a fourth embodiment of the present invention.
FIG.

FIG. 9 is an exploded perspective view of an example of a conventional photoelectric encoder.

FIG. 10: Rotating slit disk 21 and fixed slit disk 3
It is a disassembled enlarged view of 1.

FIG. 11 is a diagram showing a light flux reflection state on a reflection surface of a conventional optical encoder.

[Explanation of Codes] 11 to 14 Optical encoder 100 Rotating body 20 Rotating part main body 21 Rotating slit disk 22 Rotating slit 23 Hub 24, 24A, 24B First reflecting mirror 25, 25A, 25B of rotating part Second of rotating part Reflector 24L, 25L, 34L, 35L Reflected light erasing unit, (L
(Shaped groove / projection) 30 fixed part main body 31 fixed slit disk 32, 32A, 32B fixed slit 33 signal boundary 34, 34A, 34B first reflecting mirror 35, 35A, 35B fixed part second reflection Mirror 40 Light source part 41 Light emitting diode 42 Lens 43, 53, 61 Substrate 50 Light receiving part 51, 51A, 51B Photodiode 60 Conversion device

Claims (9)

[Claims] 1. A light source unit that emits a light beam and projects the light beam in parallel to the rotation axis of a rotating body to be measured, and a plurality of radial slits that are concentrically fixed to the rotation axis of the rotating body and are provided all around the circumference. Disk-shaped rotating portions arranged at equal intervals in a ring shape, and radially arranged at equal intervals over the entire circumference facing the slits of the rotating portion, and further, the phase number N of the signal to be detected. A disk-shaped fixed part having slits divided in the same number of rows also in the radial direction, and a light receiving part for detecting an optical signal that has passed through the slits of the fixed part and converting it into an electrical signal of a plurality of phases N, Consists of a conical first reflecting mirror and a second reflecting mirror each having an inclination angle of 45 degrees with respect to the axis and facing each other in the direction perpendicular to the axis. The light flux projected from the light source unit on the slit of the rotating unit and fixed. An optical encoder having a rotating part main body and a fixed part main body of a light guide which is guided to the light receiving part via a slit of a part, at least one of the rotating part main body and the fixed part main body.
On one reflecting mirror surface, an L-shaped annular reflected light erasing portion having surfaces perpendicular to the light beams incident on the positions corresponding to the boundaries of the optical signals of N columns adjacent to each other in the radial direction is provided. An optical encoder characterized by. 2. At least one of the rotating portion main body and the fixed portion main body is formed of a coaxial hollow hollow truncated cone-shaped transparent member having an inclination angle of 45 degrees with respect to the axis, and the first reflecting mirror and the second reflecting mirror are provided. The optical encoder according to claim 1, wherein reflecting mirrors are provided on an inner conical surface and an outer conical surface of the truncated conical transparent member, respectively. 3. The optical encoder according to claim 2, wherein at least one constituent member of the rotating portion main body and the fixed portion main body forming the light guide is formed of a transparent member. 4. The optical encoder according to claim 1, wherein the constituent member of the rotary unit main body has a hub function for connecting the rotary shaft and the rotary unit. 5. The component of the main body of the fixed part has a function of positioning the light emitting element of the light source part, and the positioning central axes of the fixed part and the light source part are on the same axis as the central axis of rotation. The optical encoder according to item 3. 6. The optical encoder according to claim 5, wherein the convex lens function of converting the light emitted from the light emitting element into a parallel luminous flux is constituted by a constituent member of the fixed portion main body or the rotating portion main body. 7. The optical encoder according to claim 1, wherein a signal conversion device for amplifying and waveform-shaping a signal detected by the photoelectric conversion element of the light receiving section is arranged on the side surface of the fixed section body facing the rotating section side. . 8. The optical encoder according to claim 7, wherein the light source section and the light receiving section are arranged on the front and back sides of the substrate of the signal conversion device, and the light reflection direction of the light guide is set according to the arrangement. 9. The labyrinth function and the gap adjusting function between the rotary unit main body and the fixed unit main body are formed by extending a peripheral portion of the fixed unit main body toward the rotary unit side in a cylindrical shape having a predetermined length. The optical encoder described in.