JPH0392716A - Photoelectric encoder - Google Patents

Abstract

PURPOSE:To achieve the compact configuration and light weight for a device and to decrease the number of components by forming a light emitting element and a lattice substrate on the light emitting side as a unitary body. CONSTITUTION:A lattice substrate 130 on the light emitting side is made to have a thin rectangular shape. Semiconductor layers 140 and 142 having the different polarities are laminated and arranged. A light emitting junction plane is formed between both layers. The layer 140 comprises P-type GaAs, and the layer 142 comprises an N-type GaAs. Mainly, near infrared-rays are emitted. Gold electrode films 144 and 146 are provided at the end surfaces of the layers 140 and 142 by the vapor deposition of gold. A high-voltage side lead wire 148 and a low-voltage side wire 150 are bonded to said films. Holes and electrons are injected into the layers 140 and 142 through said electrodes. Thus, the holes and the electrons are recombined at the contact surfaces of the layers 140 and 142. Light having the specified frequency is emitted with the electronicy excitation energy at this time. The characteristic fact of this method is that the light emitting element itself is the lattice substrate on the light emitting side. The film 144 is made to be a lattice, and slits 144a are provided at a specified interval.

Description

[Detailed description of the invention] [Industry] Second use! lil, ] The present invention provides a photoelectric encoder; Concerning the improvement of academic systems.

Especially scale and light [prior technology] Each El? Various encoders are used to detect the displacement of two parts that move relative to each other.
Photoelectric encoders are widely used because they can detect displacement without contact.

The photoelectric encoder includes a grating provided on each of two relatively moving parts, and a light emitting element and a light receiving element for detecting the overlapping of the gratings.

As such a conventional photoelectric encoder, the normal 2
In addition to the encoder that detects the overlapping of two grids, the seventh
The Journal
of the optical society
f America, 1965, vol, 55, N
o, 4, p373-381), or a reciprocal photoelectric 2 (゜4 encoder) as shown in factor 8
-1. 9 8 8 1 4) Kasa is well known.

The three-grid encoder 10 shown in FIG.
4, a reference grating 16 arranged in parallel so as to be relatively movable between the two, a light emitting element]8 disposed on the left side of the light emitting side grating 12 in the figure, and a light emitting element disposed on the right side of the detection+H side grating 14 in the figure. and a light-receiving element 20.

Then, the light emitted from the light emitting element 18 is transmitted to the light emitting side grating 1
2. Jl (reaches the light-receiving element 20 via the quasi-grating 16 and the detection-side grating 14, and the light-receiving element 20 connects each grating 12, 14 .
The limited irradiation light is photoelectrically converted by 16 and further amplified by a Brian 22 to obtain a detection signal S.

here,. ! ,k''('!The lattice king 6 is the light-emitting side lattice 12
, when moving relative to the detection side grating 14, for example in the direction of arrow X, the gratings 121, 6, .
The amount of light blocked by 14 gradually changes, and the detection signal S
is output as a substantially sine wave.

Then, the pitch P of the reference grating 16 corresponds to the wavelength of the detection signal S, and from the wavelength of the detection signal S and its division value, the i! ! 'l1! This is to measure the relative movement of the grating 16.

Therefore, the reference grating 6 is used as the main scale 24, and the light emitting side grating 12 and the detection side grating 14 are used as the index scale 26.
By installing the two scales separately, it is possible to detect the amount of phase shift of both scales.

On the other hand, FIG. 8 shows a reflective photoelectric encoder 10, and parts corresponding to those in FIG. 7 are designated by the same reference numerals and their explanations will be omitted.

In the illustrated example, the main scale 24 and the index scale 26 are made of light-transmitting glass, and the main scale 24 has a reflective 2i1;'jA grating 16.
, and the index scale 26 has a light receiving element 20
form a grid.

Therefore, in the index scale 26, the light-receiving element 20 forms a slit 1 corresponding to the light-emitting side grating 12 and the detection-side grating 14 shown in FIG.

Then, the light from the light emitting element 18 is transmitted to the collimator lens 2
8 to adjust to parallel light, index scale 26
It is illuminated from the back side of 9.j.

Light is transmitted only from the portion 5 of this viscous fruit where the light-receiving cord 20 is not formed, and is irradiated onto the main scale 24.

Furthermore, the light that has been irradiated by the reference grating 16 of the main scale 24'' travels again toward the index scale 26, and is subjected to optical conversion by the light receiving element 20.

However, 2. (The light illuminated into the gap of the quasi-grating 16 is
Since the main scale 24 is made of glass, the light passes through the main scale 24 and does not reach the light receiving element 20.

As described above, the relative movement of the main scale scale 24 and the index scale 26 will be detected by the light receiving element 20 as a substantially sinusoidal wave, similar to the method shown in FIG.

[Problem to be solved by the invention] However, for example, the transmission type 3 shown in FIG.
According to the grating photoelectric encoder, the scale is 24.26
The light-emitting element 18 and the light-receiving element 20 must be arranged on both sides of the light-emitting element 18 and the light-receiving element 20, which requires a large number of parts and is complicated to manufacture, as well as being large in size.

This point is exactly the same in the opposite type photoelectric encoder shown in Fig. 8. In particular, in the method shown in Fig. 8, a collimator lens 28 must be provided to distribute the light, and the size of the device cannot be increased. It was inevitable.

The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to provide an optical 'iLifi47 encoder that has a simple mechanism and can be made small and light-LL.

[Means for Solving the Problems] In order to achieve the above-mentioned [Object 1], the optical fIi type encoder according to the invention as set forth in Motoyama's 4-Seq. ! I (characteristically, the plate is formed from a plate-shaped light emitting element, and light-shielding shrines are arranged at regular intervals on the surface of the plate-shaped light emitting element facing the reference grid.

Further, in the photoelectric encoder according to claim 2 of the present application, the light-emitting side grating substrate is formed of a plate-shaped light-emitting element, and the light-receiving elements are arranged at intervals of 1') degrees Celsius in one part of the plate-shaped light-emitting element. It is characterized by

[Function] Since the photoelectric encoder according to the present invention has the above-described means, the light-emitting side grating substrate and the light-emitting element are integrally formed, and the number of parts can be reduced and the encoder can be made smaller and lighter.

In addition, in the reflective photoelectric encoder, since the grid-like light receiving element is formed on the light emitting element that constitutes the light emitting side grid plate, the light emitting element, the light receiving element, the light emitting side grating, and the light receiving side grating are all integrated. It becomes possible to construct the structure with a separate shrine, further reducing the number of parts and making it smaller and lighter in damage.

[Dog Example] Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings 21 (11'IJ1). Parts corresponding to those in the prior art are designated by the reference numeral 100 and their explanation will be omitted.

FIG. 1 shows an external perspective view of a light-emitting side grating substrate used in a photoelectric encoder according to an embodiment of the present invention.

The light-emitting side grating 2 (plate 130) shown in the same figure is constructed in a thin rectangular shape, and has small conductors 11"i 1 4 0 with different polarities.
, 142 are arranged in a stacked manner to form a light-emitting bonding surface between them.

In this embodiment, the first semiconductor layer 140 is made of P-type Ga.
As, the second semiconductor layer 142 is made of N-type GaAs,
It mainly emits near-infrared light.

Further, metal films 144, 146 for electrodes are formed on the edges of both the semiconductor layers 14.0.142 by vapor deposition of gold.

A high voltage side lead wire 148 and a low voltage side lead wire 150 are bonded to the metal strips 1.44 and 146 for both electrodes, respectively.
- The conductor 1c is injected with an iL hole and an il element into the rt4o, 142.

Therefore, the holes and electrons injected in this way recombine at the junction between both semiconductor layers 140 and 142, and at this time, the electron excitation energy causes light emission at a predetermined frequency.

= 9? A characteristic feature of the invention is that such a light emitting element itself serves as a grating substrate on the light emitting side. Therefore, in this embodiment, the metal film 144 on the side from which the light emitted is emitted to the outside forms a grating. are doing. That is, in this embodiment, a plurality of slits t-144a are provided at regular intervals in the electrode metal 11Q144.

The slits are configured, for example, with a pitch of 20 μm and a slit of 10 μm.

Therefore, the light emitted from the bonding surface is emitted to the outside from the slit h 1 4 4 a of the electrode metal film 144, and the luminous flux shape of this light beam is 11I''. :J 1 4 4
It is determined by the slit shape of a.

In this embodiment, the electrode metal film 146 on the opposite side covers the entire second semiconductor layer 142, and the side surfaces of the semiconductor layers 140, 14.2 have a thickness of 14V<, and a bonding surface. Since they are perpendicular to each other, there is little loss of light emitted from these surfaces to the outside, and the light emitted from the bonded surfaces is efficiently slit) ■ 1 4 4. It can be emitted from a. Of course, it is also preferable to shield the side surfaces from light with black paint or the like.

Further, in the present invention, both semiconductor layers 140 and 142 can be arranged with their polarities, that is, pH2 and NUR, reversed.

In addition, in this example, it was decided to emit near-field light, but
For example, it is also suitable to use GaP or (GaAl)As as the semiconductor, and it is possible to emit visible light if necessary.

In addition to the above-mentioned vapor deposition, the metal film for electrodes can be formed using
Sputtering and other arbitrary methods can be used.

FIG. 2 shows a state in which the light-emitting side grating 21 (plate 130 shown in FIG. 1) is used in a photoelectric linear encoder.

That is, the reference grating 1 moves relatively according to the length of the object to be measured.
16, the light emitting side grating 12, and the detection side grating 114 make up a 3 grating system.

In this embodiment, there are four detection gratings 114a, 114b, . . . each consisting of an index scale.
114c, and light receiving elements 120a, 120b, -120c are arranged corresponding to each detection grating. Each detection grid 1 1. 4a, . . . 114C are formed with vertical striped scales whose pitches are shifted by 90 degrees from each other. As a result, each light receiving element 120a. ,...
A phase with a phase shift of π/2 from 120c,
B-phase, A-phase, and B-phase signals can be obtained, and the A-phase output whose amplitude is amplified by the A-phase and the A-phase, and the B-phase output whose amplitude is also amplified by the B-phase and the B-phase are obtained. The A phase output and B
The direction of relative movement of the scale is discriminated based on the direction of phase shift of the phase output, etc., and the detection signal is electrically divided to perform displacement detection with high resolution.

Here, in this embodiment, as described above, the light-emitting side grating plate 130 is formed from a light-emitting element, and the light-emitting side grating 1 and 2 are formed directly on the light-emitting element, so compared with FIG. As is clear from the above, efforts have been made to reduce the number of parts and make the shape more compact.

FIG. 3 shows a schematic structural diagram of a photoelectric encoder according to a second embodiment of the present invention, and portions corresponding to those in FIG.

The characteristic feature of this embodiment is that the light emitting side grating substrate 23
0 is formed from a light emitting element, and the detection side grating) U (plate 232) is formed from a light receiving element.

That is, the detection-side grating substrate 232 according to this embodiment has the fourth
It is constructed as shown in the figure.

In FIG. 4, the detection-side grating substrate 232 has a first signal deriving material layer 252 made of a light-shielding and conductive material, such as a metal film, on a light-transmitting material 250 made of glass, for example, and converts light into electrical signals. A PN semiconductor layer 254 that converts into
or a second signal deriving material layer 256 made of a mixture thereof
The light-receiving portion 258 is formed by laminating , and in this order, and is formed into a thin tangle-like shape at a constant pitch.

The detection side grating board 232 has its light receiving section 258 disposed to face the main scale 224, and each light receiving section 258 is arranged to face the main scale 224.
8 serve as the slits of the light receiving elements 120-13-1 and the detection side grating 114 in FIG.

Note that the light that has passed through the second signal deriving material layer 256 of the light receiving section 258 reaches the PN semiconductor layer 254, is photoelectrically converted at the interface between the N-type non-quality silicon film 260 and the P-type non-quality silicon film 262, and is sent to the output terminal. 264 and 266 to the outside.

As described above, according to the photoelectric encoder according to the second embodiment of the present invention, the light emitting side grating substrate is integrated with the light emitting element, and the detection side grating 2l (the plate is integrated with the light receiving element). As a result, the number of parts can be further reduced and the size and weight can be reduced.

FIG. 4 shows a photoelectric encoder according to a third embodiment of the present invention, and portions corresponding to those in the second embodiment are designated by the reference numeral 100 and their explanation will be omitted.

The characteristic feature of this embodiment is that in a reflective photoelectric encoder, a light emitting side grating substrate, a light emitting element, a detecting side grating substrate, and a light receiving element are integrally formed14.

That is, in FIG. 5, the index scale 370 is
The substrate is composed of an elongated light emitting element 372, and a light receiving section 358 is formed on one surface thereof.

Therefore, the light emitted from the light emitting element 372 is reflected by the IIli quasi-lattice 316 of the main scale 324 and reaches the light receiving section 358.

At this time, the light receiving parts 358 formed at regular intervals on the light emitting element 372 serve as a grid on the light emitting side, and the light receiving parts 358 themselves are formed in a grid shape on the light emitting side. It also serves as a lattice.

Here, the detailed structure of the index scale 370 is shown in FIG.

As is clear from the figure, the light emitting element 372 is formed from a P-type semiconductor layer 340 and an N-type semiconductor layer 342.

Light receiving portions 358 are formed at regular intervals on the elongated light emitting element 372J.

The depiction of each light receiving section 358 is as shown in FIG. 4 above.

Next, a method for manufacturing the index scale 370 according to this embodiment will be described.

First, a long light emitting element 372 is formed by a conventional method.

Then, the light emitting cord 372 is installed in a vacuum deposition equipment,
1 in a vacuum environment of 5 x 10 -6 torr.
Heating to 50~200℃, Cr from tungsten board
Cr is vapor-deposited on the light emitting element 372'', and Cr is vapor-deposited on the light emitting element 372''.
A Cr film that becomes the first signal deriving material layer 352 is formed to have a thickness of 0.000 to 3000.

Next, the light emitting element 372 on which the Cr film was formed was placed in a plasma chamber and heated to 300"C, and SIT
A gas obtained by diluting Ar gas containing 10% -I4 ten times with H2 gas is introduced into the plasma chamber. Then, an N-type non-quality silicon (Na-Si) film 360 is formed by high-frequency glow discharge under a pressure of 0.1 to 2 torr.
and P-type non-quality silicon (P a Sl) IK'3
62 is laminated on the first signal deriving material layer 352, thereby forming a semiconductor layer 354 with a thickness of about 1 μm.

The N-type non-crystalline silicon film 360 is formed by adding a small amount of PH3 into the reaction gas at the initial stage of deposition, and the P-type non-quality silicon film 362 is formed by adding 13% of the PH8 to the reaction gas during the deposition.
2r-1 and 6, respectively. Here, I) The N semiconductor layer 354 can also be formed by other methods such as a thermal decomposition method and a sputtering deposition method.

Next, the light emitting element 372 with the PN semiconductor layer 354 formed thereon is placed in a vacuum evaporated layer, heated to 150° C., and In20a placed in an alumina pot is deposited with about 100
A second signal deriving material layer 356 is deposited as a human-thick In203 film on the PN semiconductor layer 354.
form.

Next, a photoresist is applied to a thickness of about 2 μm using a spin coating method and dried. Furthermore, after shielding the output terminal portion 366 from light with a mask, the photoresist on the output terminal portion 366 is removed by exposure to ultraviolet light and development.

Next, the second signal deriving material layer 356 and the PN semiconductor layer 354 of the output terminal 366 portion 17 are removed by a method such as chemical etching or plasma etching, and the first signal deriving layer 352 is exposed.

Similarly, the light guide slit 374 between the light receiving sections 358
The first and second signal guiding material layers 352, 3 corresponding to the light guiding slits 374 are covered with photoresist except for the first and second signal guiding slits 374.
56 and the PN semiconductor layer 354 are removed by plasma etching or the like to expose the light emitting element 372.

Note that it is preferable that the width of the light guide slit 374 is at least twice the height of the light receiving section 358 from the surface of the light emitting element 372 to detect brightness and darkness.

Next, the first signal derivation layer 352 and the second signal derivation layer 35
The conductor wire for extracting the output J current from 6 is attached to the output terminals 364 and 366 using conductive wire adhesive.Finally, in order to protect the PN semiconductor chips, apply a thin layer of silicone varnish to the entire surface and dry. make it complete.

As described in Section 2 below, according to the photoelectric encoder according to this embodiment, it is possible to configure a photoelectric L (14 encoder) with a 3-grid system using only the two-part system of the index scale and the main scale, and the number of parts can be reduced. It is possible to achieve a significant reduction in the size of the device and to make the device smaller and lighter.

In each of the above embodiments, the three-grid photoelectric encoder was mainly described, but the present invention is also applicable to a normal two-grid photoelectric encoder.

In addition, although the above embodiments have been described using a linear encoder as an example, the present invention is not limited to this, and can also be applied to a rotary encoder, for example.

[Effects of the Invention] As explained, according to the photoelectric encoder of the first foil claim 1 of the present application, the light emitting element and the light emitting side grating substrate are integrally formed, so that the device can be made smaller and smaller. , and the number of parts can be reduced.

Further, according to the photoelectric encoder according to claim 2 of the present application, the light emitting element, the light emitting side grating substrate, the light receiving element, and the detecting side grating star plate are integrally formed, so that the number of parts can be further reduced and the device can be improved. It is possible to make the device smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a light-emitting grating plate used in a photoelectric encoder according to a first embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a photoelectric encoder according to a first embodiment, and FIG. The figure is a schematic structural diagram of a photoelectric encoder according to the second embodiment of the present invention, FIG. 4 is an explanatory diagram of the detection side grating 2l (plate) used in the second embodiment, and FIG. An explanatory diagram of a photoelectric encoder according to an embodiment; FIG. 6 is an explanatory diagram of an index scale used in a photoelectric encoder according to a third embodiment; FIG. 7 is a schematic configuration diagram of a conventional three-grid photoelectric encoder; Fig. 8 is a schematic explanatory diagram of the conventional anti-betsu-style encoder. 10, 11. 0, 210, 310... Encoder, 24
．． 124 224...Main scale, 26,12
6,226...index scale, 1.30,2
30... Light-emitting side grating plate, 232... Light-receiving side grating board, 370... Index scale.

Claims (2)

[Claims] (1) A main scale on which a predetermined reference grating is formed; and an index scale arranged in parallel movably relative to the main scale and on which a predetermined light-emitting side grating is formed; In a photoelectric encoder that receives light restricted by a grating and outputs the amount of relative movement between the main scale and the index scale, the light emitting side grating substrate is formed of a plate-shaped light emitting element, and a thin film-shaped is formed on the surface opposite the reference grating. A photoelectric encoder characterized by light shielding materials arranged at regular intervals. (2) a main scale on which a predetermined reference grating is formed; and an index scale arranged in parallel so as to be movable relative to the main scale, and on which a light-emitting side grating and a light-receiving side grating are formed, and the light-emitting side grating In a photoelectric encoder that outputs the amount of relative movement between the main scale and the index scale by reflecting the light transmitted through the reference grating and further restricting the light by the detection side grating, the light emitting side grating substrate is connected to a plate. light emitting elements arranged at regular intervals on one side of the plate-shaped light emitting element, light emitted from the light emitting elements is reflected by a reference grating of the main scale via between the light receiving elements, and the light emitting element A photoelectric encoder characterized in that light is received by an upper light receiving element.