JP3490128B2 - Photoelectric encoder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoder for detecting displacement information generated by movement such as rotation with high accuracy, and more particularly to a photoelectric encoder using a light emitting element such as a semiconductor laser.

[0002]

2. Description of the Related Art A rotary encoder will be described as an example of a photoelectric encoder.

Rotary encoders that detect rotational displacement with high accuracy are widely used for applications such as capstan motors for OA equipment, NC machine tools, VTRs, rotating speeds of rotating drums, and fluctuations in rotating speeds. Has been. First, a configuration example of an optical unit of a conventional type rotary encoder will be described.

FIG. 6 is a diagram showing an example of the structure of an optical section of a conventional type rotary encoder. The optical unit includes a semiconductor laser 411, a collimator lens 412, a beam splitter 413, a photodetector 414, a rotary plate 415 having a transmission diffraction grating radially formed at high density, reflection mirrors 416, 4.
It is equipped with 17. To explain the operation, the semiconductor laser 4
The laser light beam 418 emitted from 11 is converted into a parallel light beam 419 by the collimator lens 412, passes through the beam splitter 413 as it is, and travels toward the rotating plate 415. Then, it is diffracted by the transmission type diffraction grating of the rotating plate 415, and the first-order diffracted light 422 and the minus first-order diffracted light 4
Yields 23. The diffracted lights 422 and 423 are individually reflected by the reflection mirrors 416 and 417, and return to their original optical paths. Then, the beam splitter 413 bends the optical path by 45 ° and enters the photodetector 414. Here, the interference light is photoelectrically converted, and the rotation state is detected as a sine wave signal as shown in FIG.

FIG. 7 is a diagram showing another example of the configuration of the optical section of a conventional rotary encoder. This optical unit includes a semiconductor laser 511, a collimator lens 512, a beam splitter 513, a photodetector 514, a rotating plate 515 having a transmission type diffraction grating radially formed at high density, and a reflecting mirror 51.
6,524,525. In this configuration, the laser light flux 518 emitted from the semiconductor laser 511 is converted by the collimator lens 512 into a parallel light flux 519. This light beam 519 passes through the beam splitter 513 as it is, is reflected by the reflection mirror 524, and is reflected by the reflection plate 515.
The light beam 521 heading for 5 is branched. These two luminous flux 5
Angles of the reflection mirrors 524 and 525 are adjusted so that the light beams 20 and 521 are incident on the same point of the rotary plate 515. Light flux 52 incident on the transmission type diffraction grating of the rotating plate 515
The incident angles of 0,521 are respectively adjusted to the ± first-order diffraction angles of the light rays that are vertically incident on the diffraction grating. As a result, both the light fluxes 520 and 521 are rotated by the rotating plate 515.
After being diffracted by the transmission diffraction grating of, the light is emitted in a direction perpendicular to the rotating plate 515. The ± first-order diffracted lights 523 are reflected by the reflection mirror 516, diffracted again by the transmissive grating of the rotating plate 515, then return to their original optical paths as ± first-order diffracted lights, and are superposed via the beam splitter 513. It is caused as interference light. After that, the light enters the photodetector 514, is photoelectrically converted here, and detects the rotation state as a sine wave signal as shown in FIG. 8 similarly to the above configuration example.

[0006]

However, as shown in FIG.
A conventional type rotary encoder as shown in FIG.
Optical element components (semiconductor laser, collimator lens,
Beam splitters, etc.) must be individually provided, and the optical axes of these must be precisely adjusted and fixedly arranged. For this reason, a large number of man-hours are required for manufacturing, and there is a limit in reducing the price.

Further, since the beam is split by the beam splitter, there is a limit to miniaturization of the optical section.

The present invention has been made in view of the above problems, downsizing,
It is an object of the present invention to provide a photoelectric encoder that can be thinned and reduced in cost.

[0009]

According to a first aspect of the present invention , a semiconductor laser is provided on the front and back surfaces of a light transmitting body forming an optical path.
Light-emitting element such as, etc., receives light from the light-emitting element and forms a parallel light flux
Hologram collimating lens for
Light to the outside and deflect the incident light from the outside.
Hologram deflector and deflection from the hologram deflector
A photoelectric element including a photodetector that receives incident light is arranged to
The faculty is integrally formed and emitted from the hologram deflector.
The optical information is made to carry the displacement information of the moving body by the generated light.
Information carrying means for entering the hologram deflector of
As the information carrying means, is the light input / output section of the optical section?
The light emitted from the transmission is transmitted by a transmission type diffraction grating.
Reflects light that has passed through the moving body and the transmission diffraction grating
Then again pass through the transmissive diffraction grating and
It is characterized in that it is provided with an external reflection mirror which is incident on the projection part .

The invention described in claim 2 is the same as that described in claim 1.
In the photoelectric encoder on board, semiconductor laser, light detection
Parts that require external wiring, such as
The plate is fixed to the light-transmitting body, and these parts are attached to the light-transmitting body.
It is characterized by being integrated .

[0011]

[0012]

[0013]

According to the first aspect of the present invention, photoelectric elements such as a semiconductor laser and a hologram collimating lens are provided on the front and back surfaces of the light transmitting body, and are miniaturized as an integrated part including an optical path. At this time, since the collimating function and the function of the beam splitter are configured by the hologram, these parts are small and thin. In this way,
Parts including collimating lens (hereinafter referred to as optical part)
Since it is integrated and miniaturized, the encoder as a whole can be miniaturized. In addition, the light emitting element,
Since the collimator lens and the like are previously configured as an integrated part, the assembly of the device is simplified. Also hologram
The light emitted from the deflector is transferred through a transmission type diffraction grating.
After being transmitted by the moving object, it is reflected by the reflecting mirror.
After passing through the transmission type diffraction grating again,
It is incident on the Gram deflector. And that light is a photodetector
Is incident on.

In the invention described in claim 2, the semiconductor
Parts requiring external wiring such as body laser and photodetector are on the board
And then fixed to the light transmitting body. According to
For components such as semiconductor lasers and photodetectors,
By positioning on the transmissive body, it is possible to position them at the same time.
It becomes easy to integrate the body into the front and back. Wiring with the outside is required
Another important component is the detection signal processing circuit of the photodetector.
Etc. can be given. In addition, hologram collimate
Lenses, hologram deflectors, hologram condenser lenses, etc.
It can be formed of a known photoresist or the like.

[0015]

[0016]

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In addition, since the rotary encoder is shown as an example in the following embodiments, a rotary plate is used to obtain displacement information.However, in the case of an encoder that detects a position in a linear direction, a transmission type diffraction plate is used on a moving flat plate. A list of grids is used.

FIG. 1 is a diagram showing a configuration example of a rotary encoder which is a first embodiment of the present invention.

The rotary encoder includes a semiconductor laser 11 and a reflection film 1 on the upper surface of a transparent block (light transmitting body) 16.
3, an optical unit including a photodetector 15, a hologram collimator lens 12 that reflects light on the lower surface, a light-transmissive hologram deflector 14, a rotating plate 21, and external reflection mirrors 22 and 23. .

A structural example of the optical section is shown in a perspective view in FIG.

The transparent block 16 is made of glass or the like,
It is formed in a block shape with a thickness of about several mm. The hologram collimator lens 12 and the hologram deflector 14 are formed on the transparent block 16 by a semiconductor process technique using a mask. The reflective film 13 can be formed by a method such as aluminum vapor deposition. The semiconductor laser 11 and the photodetector 15 include a transparent block 16
Mounted on the surface of.

The rotary plate 21, and the external reflection mirror 22,
The configuration of 23 is similar to that of the conventional one shown in FIG. 6, and a transmission type diffraction grating is radially formed at a high density on the rotary plate 21.

The operation of this rotary encoder will be described.

First, the beam from the semiconductor laser 11 arranged on the upper surface 17 of the transparent block 16 enters the transparent block 16 and hits the hologram collimating lens 12 arranged on the lower surface of the transparent block 16. here,
The beam is converted into a parallel light beam, and the transparent block 16
It is reflected diagonally upward in the interior. The parallel light flux is reflected obliquely downward by the reflection film 13 provided on the upper surface of the transparent block 16, and then hits the hologram deflector 14 provided on the lower surface 18 of the transparent block 16. The parallel luminous flux is diffracted in the normal direction of the lower surface 18 of the transparent block 16 while passing through the hologram deflector 14, and propagates in the direction of the rotary plate 21 on which the transmission type diffraction grating is formed. Then, the light flux 20 is diffracted by the transmissive diffraction grating formed on the rotating plate 21, and ± first-order diffracted lights 24 and 25 are generated. The ± first-order diffracted light 24, 25 is reflected by the external reflection mirror 22,
At 23, the light is reflected in the direction of the original optical path, again diffracted by the rotary plate 21 on which the transmission diffraction grating is formed, and hits the hologram deflector 14 on the lower surface 18 of the transmission block 16. Then, here, the light is diffracted in a direction different from that of the reflection film 13 and is incident on the photodetector 15 (where the direction toward the reflection film 13 is the plus first-order diffraction direction, the direction of the photodetector 15 is the minus first-order diffraction direction). Equivalent to). The incident light is photoelectrically converted to obtain a signal for detecting the rotation state as shown in FIG.

Thus, on the surface of the transparent block 16,
Semiconductor laser 11, hologram collimating lens 12,
Since the optical elements such as the reflection film 13, the hologram deflector 14, and the photodetector 15 are arranged, each optical element only needs to be positioned with respect to the transparent block 16, which simplifies the positioning work. Further, since each optical element as described above is arranged on the surface of the transparent block 16 having a thickness of about several mm, the rotary encoder is small and thin as a whole.

Although the reflective film 13 is provided in this embodiment, the hologram collimator lens (12) is arranged at the position of the reflective film 13 and the semiconductor laser (11) is provided on the left side of the position of the hologram collimator lens 12. It is also possible to omit the reflection film 13 by arranging).

FIG. 3 is a diagram showing a configuration example showing a second embodiment of the rotary encoder.

This rotary encoder has a rotary plate 122.
The light is emitted from two directions. The optical part is formed on the upper surface of the transparent block 119 by the semiconductor laser 1
11, two reflective films 113 and 116, two photodetectors 1
15, 118, and the collimating lens 11 is provided on the lower surface.
Two or two transmissive hologram deflectors 114 and 117 are provided. Further, below the optical portion, a rotating plate 122 having a transmission type diffraction grating and an external reflection mirror 123.
Is provided.

The operation of this configuration will be described.

The beam from the semiconductor laser 111 arranged on the upper surface 120 of the transparent block 119 is transmitted through the transparent block 1.
19 and hits the hologram collimator lens 112 disposed on the lower surface 121 of the transparent block 119, where it is converted into a parallel light beam, and the transparent block 119
Inside, it is reflected in two directions diagonally upward. Each of these corresponds to the direction of plus first-order diffraction and the direction of minus first-order diffraction. The two parallel light fluxes are respectively reflected by the two reflection films 11 provided on the upper surface 120 of the transparent block 119.
It is reflected obliquely downward at 3, 116, and then hits two hologram deflectors 114, 117 arranged on the lower surface 121 of the transparent block 119, respectively. The two parallel light beams are diffracted at a certain angle with respect to the lower surface 121 of the transparent block while passing through the hologram deflectors 114 and 117. The diffracted lights 124 and 125 propagate in the direction of the rotary plate 122 on which the transmission diffraction grating is formed. Just two diffracted lights 12 on the rotating plate 122
4,125 are incident on the same point. The incident angles of the light beams 124 and 125 that enter the transmissive diffraction grating of the rotating plate 122 are adjusted to the ± first-order diffraction angles of the light rays that are perpendicularly incident on the diffraction grating.
The two light beams are diffracted by the transmissive diffraction grating on 2, and both are emitted in the normal direction of the rotating plate 122, and the two light beams overlap. The light flux 126 is reflected in the original optical path direction by the external reflection mirror 123, and is again diffracted in the ± first-order directions by the rotary plate 122 on which the transmission diffraction grating is formed.
Hologram deflector 1 on lower surface 121 of transparent block 119
14 and 117 are hit, respectively, and here, as zero-order light, they pass through the hologram deflectors 114 and 117, respectively, and enter the photodetectors 115 and 118. Here, each signal is photoelectrically converted, and a signal for detecting the rotation state is obtained by performing an arithmetic operation in a signal processing circuit for integrating the outputs of both.

Also in this embodiment, as in the above embodiment,
Since the optical element is arranged on the surface of the transparent block 119, the positioning becomes easy, and the size and thickness can be reduced. Further, since there is only one external mirror (only 123), positioning during assembly can be further facilitated.

FIG. 4 is a diagram showing a configuration example showing a third embodiment of the rotary encoder.

This rotary encoder has a rotary plate 231.
Is a reflection type. The optical unit of this rotary encoder includes a semiconductor laser 221, a reflection film 223, and a photodetector 225 on the upper surface of a transparent block 226, and a hologram collimator lens 222 and a hologram condenser lens 224 on the lower surface. A rotary plate 231 having a reflection type diffraction grating is provided below the optical section. The hologram condenser lens 224 can be formed by a semiconductor process technique using a mask. In addition, the rotating body 231 is
A reflection type diffraction grating 232 is provided on the upper surface of a plate-shaped rotating body in a radial pattern from the rotation axis. This reflection type diffraction grating is made of a material having a high light reflectance, and is formed in, for example, an elongated thin projection shape.

The operation will be described.

The beam from the semiconductor laser 221 arranged on the upper surface 227 of the transparent block 226 is transmitted through the transparent block 2.
26, and hits the hologram collimating lens 222 disposed on the lower surface 228 of the transparent block 226, where it is converted into a parallel light beam, and the transparent block 22
It is reflected obliquely upward in the area 6. The parallel luminous flux is reflected by the reflective film 223 provided on the upper surface 227 of the transparent block 226.
Is reflected obliquely downward by the holographic condenser lens 224 disposed on the lower surface 228 of the transparent block 226.
Incident on. The parallel light flux is generated by this hologram condenser lens 2
After passing through 24, it is just focused on the rotary plate 231 on which the reflection type diffraction grating 232 is formed. By condensing light near the diffraction limit, the reflection type diffraction grating 232 and the steps in the periphery thereof function as a diffraction grating in the zero-order reflected light, and the ± first-order diffracted light components generated are reflected from the rotating plate 231 while overlapping. Then, the lower surface 228 of the transparent block 226
Hit the hologram condenser lens 224 of the
After being diffracted obliquely upward in the direction opposite to 3, the photodetector 2
It is incident on 25. Here, assuming that the direction toward the reflection film 223 is the plus first-order diffraction direction, the direction toward the photodetector 225 corresponds to the minus first-order diffraction direction. Then, the incident light is photoelectrically converted, and a signal for detecting a rotation state as shown in FIG. 8 is obtained.

Also in this embodiment, in the optical section,
Since the optical element is disposed on the surface of the transparent block 226, it is not necessary to align the optical elements with each other, and the manufacturing process including the alignment and the like is facilitated and the rotating body 2 is provided.
Since 31 has the reflection type diffraction grating 232, an external mirror is unnecessary, the number of parts of the entire rotary encoder is reduced, the number of manufacturing steps can be reduced, and the apparatus itself can be made small and thin.

FIG. 5 is a diagram showing the construction of the optical portion of the rotary encoder of the fourth embodiment.

In this embodiment, the semiconductor laser and the photodetector of the optical section are integrated into a single integrated circuit board, and the whole manufacturing process can be simplified. In the embodiment shown in FIG. 5, the configuration of the apparatus itself is the same as that of the embodiment shown in FIG. In the figure, a semiconductor laser 311 and a photodetector 315 are shown as one integrated circuit board (optical integrated circuit board) 3
19 integrated. The optical integrated circuit board 31
9 may also include a photodetection signal processing circuit and the like. The semiconductor laser 311 and the photodetector 315 can be integrally fixed to the optical section by adhering the optical integrated circuit board 319 to the transparent block 16.

In this embodiment, the semiconductor laser and the photodetector of the first embodiment are mounted on the optical integrated substrate and then fixed to the transparent block. However, the second embodiment (FIG. 3). Similarly, in the third embodiment (FIG. 4), the semiconductor laser and the photodetector may be mounted on the optical integrated circuit board and then fixed to the transparent block.

[0040]

According to the invention described in claim 1, since the photoelectric elements such as the semiconductor laser and the hologram collimating lens are integrally formed on the front and back surfaces of the light transmitting body, the number of parts at the time of assembly is reduced. And the assembly process becomes simple.
In addition, collimator lens and beam splitter (deflector)
Since this is composed of a hologram, these parts are made thin, and it is possible to make the size and thickness thin as a whole.

[0041]

According to the second aspect of the invention, components such as a semiconductor laser and a photodetector that require wiring to the outside are mounted on the substrate and then fixed to the light transmissive body. After forming the parts that require these wiring as an optical integrated circuit board in one area, by fixing the optical elements such as holograms to the light transmissive body that has been integrally formed in advance, the assembly man-hours can be greatly reduced. It is possible to realize low price.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention and is a diagram showing a configuration example of a rotary encoder.

FIG. 2 is a perspective view showing a configuration of an optical section of the rotary encoder.

FIG. 3 is a diagram showing a second embodiment of the present invention and is a diagram showing a configuration example of a rotary encoder.

FIG. 4 is a diagram showing a third embodiment of the present invention and is a diagram showing a configuration example of a rotary encoder.

FIG. 5 is a diagram showing a fourth embodiment of the present invention, and is a diagram showing a configuration of an optical integrated optical unit.

FIG. 6 is a diagram showing a configuration example of a conventional rotary encoder.

FIG. 7 is a diagram showing another configuration example of a conventional rotary encoder.

FIG. 8 is a diagram showing a state of a detection signal of a rotary encoder.

[Explanation of symbols]

11 Semiconductor laser 12 Hologram collimating lens 13 Reflective film 14 Hologram deflector 15 Photodetector 16 Transparent block (light transmitting body) 21 Rotating plate with transmission type diffraction grating 22,23 Reflection mirror

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takehisa Ishihara 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture Sharp Corporation (56) Reference JP-A-5-215574 (JP, A) JP-A-63- 277924 (JP, A) JP-A-3-113316 (JP, A) JP-A-3-217992 (JP, A) JP-A-5-103154 (JP, A) Actual development Sho 61-12016 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01D 5/26-5/38 G01B 11/00-11/30

Claims (2)

(57) [Claims] 1. A semiconductor is provided on the front and back surfaces of a light transmitting body that forms an optical path.
Light-emitting element such as body laser, receives light from the light-emitting element, and
Hologram collimating lens for making a parallel light flux, the parallel light flux
Of the incident light from the outside and deflect the incident light from the outside.
Hologram deflector for directing, and the hologram deflector
A photoelectric element including a photodetector on which polarized light from
The optical part is integrally formed, and the moving body is displaced by the light emitted from the hologram deflector.
It carries information and enters the hologram deflector in the optical section.
The information carrying means for emitting light is used as the information carrying means.
The light emitted from the transmission is transmitted by a transmission type diffraction grating.
Reflects light that has passed through the moving body and the transmission diffraction grating
Then again pass through the transmissive diffraction grating and
It is characterized by having an external reflection mirror that makes it enter the projecting section.
Photoelectric encoder. 2. The photoelectric encoder according to claim 1.
Te, semiconductor lasers, external wiring groups necessary parts such as an optical detector
It is integrated on a plate and the substrate is fixed to the light transmitting body
Photoelectric devices characterized by integrating these components into a light-transmitting body
Expression encoder.