JPS6355416A - Optical rotary encoder - Google Patents

Abstract

PURPOSE:To prevent a inconvenience caused by a fact that a load is applied in the axial direction of an encoder, and also, to reduce the outside diameter dimension of a cord wheel, by constituting the titled encoder so that the cord wheel in which many rotary slits have been formed on the peripheral surface is inserted externally and attached to a revolving shaft. CONSTITUTION:A light projecting element 4 is placed so that roughly parallel light beams are projected in the axial direction, the light beams projected from the light projecting element 4 are reflected first in the diameter direction by a reflecting surface 8 of a V-shaped groove 7, and the reflected light beams transmit through a half mirror surface 9, and thereafter, intermitted by a rotary slit of a cylindrical cord wheel 2a and a fixed slit of a phase plate 3a. Subsequently, the intermitted light beams which have been reflected by the reflection type phase plate 3a is reflected in the axial direction by the reverse side of the half mirror surface 9,and received detected by a light receiving element 5. Also, light beams in the axial direction are projected from the light projecting element 4, this light beams is reflected in the diameter direction by the reflecting surface 8, and the light beams which have been intermitted by the slit is reflected by the half mirror surface 9 and received by the light receiving element 5. In this way, an inconvenience caused by a fact that a load is applied in the axial direction can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to an optical rotary encoder that performs position detection for measurement and feedback control in robots, machine tools, recorders, and the like.

[Background technique? ! 1 Conventionally, this type of optical rotary encoder that detects position for measurement and feedback control in robots, machine tools, recorders, etc. has a flat code wheel 2 as shown in FIGS. 2 and 3. A phase plate 3 is fixed to the rotating shaft 1 and placed opposite the code wheel 2 with a slight gap, and light emitting elements 4 such as light emitting diodes are mounted on both sides of the code wheel 2 and the phase plate 3. 7o) It has a structure in which a light receiving element 5 such as a transistor or a solar cell is arranged.

Here, the code wheel 2 is formed by drilling a large number of rotating slits 10 at equal intervals around the circumference of a disc, as shown in FIG. ) As shown in FIG. It is supposed to be done.

However, in such a conventional example, when a load is applied in the axial direction, the rotating shaft 1 is displaced and the code wheel 2 and the 7-ize plate 3 come into contact, or the code wheel 2 is damaged. There was a problem. Therefore, in order to eliminate this inconvenience, as shown in FIG. An arc-shaped 7A spray plate 3a having an appropriate number of fixed slits 11 is arranged opposite to the outer peripheral surface of the code wheel 2a, and light is emitted and received through both slits i o and i i. Some devices detect the rotation angle of the rotating shaft 1 based on changes in light. Here, the light projecting element 4 and the light receiving element 5 are arranged in the radial direction with the code wheel 2a and the code wheel 7a being interposed therebetween. In such a conventional example, even if the load in the axial direction decreases,
There is no risk that the code wheel 2a and the code wheel 7A's plate 3g will come into contact with each other, and problems with direct alignment due to axial loads can be prevented, but the light emitting element 4 and the light receiving element 5 are arranged in a straight line in the radial direction. Since it is necessary to provide a space for arranging the light projecting element 4 within the hood wheel 2a, there is a problem in that the outer diameter of the code wheel 2a becomes large, making it impossible to downsize the code wheel 2a.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to prevent the inconvenience caused by the load being applied in the axial direction, and to prevent the inconvenience of the code wheel. To provide an optical Loklienfug which can be easily miniaturized by reducing its outer diameter.

[Disclosure of the Invention] (Embodiment 1) Fig. 1 shows an embodiment of the present invention, in which a transparent cylinder is formed with a large number of rotating slits 7) 10 on the circumferential surface, for example, by etching a metal vapor deposited film. A code wheel 2a consisting of a body is attached externally to the rotating shaft 1, a V'4-groove 7 is bored in the rotational direction on one end surface of the code wheel 2a, and a reflective surface is formed on the side surface of the rotating shaft of the character II7. 8 and a half-mirror surface 9 on the outer surface, and a reflective type 7A spray plate 3a having an appropriate number of fixed slits 11 formed opposite the outer peripheral surface of the code wheel 2a, and The light emitting element 4 is arranged so as to emit light substantially parallel to the mirror surface 8, and the light reflected in the radial direction by the reflecting surface 8 and transmitted through the half mirror surface 8 is interrupted at the slits 10.11 and 10. The light receiving element 5 is arranged so as to receive the light reflected from the back surface of the half mirror surface 9 and substantially parallel to the axial direction. In addition, case 13 is
It is formed of a cylindrical case body 14 and an end plate 16 equipped with a bearing 15, and the light emitting element 4 and the light receiving element 5 are mounted on printed circuit boards 17a and i7b, respectively.

The operation of the embodiment will be described below. Now, the light projecting element 4 is arranged so as to project light substantially parallel to the axial direction, and the light projected from the light projecting element 4 is first
The reflected light is reflected in the radial direction by the reflective surface 8 of the groove 7, and after passing through the half mirror surface 9, the reflected light passes through the food wheel 2.
It is interrupted by the rotating slit 10 of a and the fixed slit 11 of 7 ace play) 3a. The intermittent light reflected by the reflective phase plate 3a is reflected in the axial direction by the back surface of the half mirror surface 9, and is received by the light receiving element 5. The optical path is indicated by an arrow in FIG. In this way, in the present invention, since the cylindrical food wheel 2a is used, even if a load is applied in the axial direction, the rotary shaft 1 is displaced and the code wheel 2 and phase plate are displaced as in the conventional example shown in FIG. 3 will not come in contact with each other or the code wheel 2 will not be damaged. In addition, the light projecting element 4
10. The light interrupted in step 11 is reflected by the half mirror surface 9 and received by the light receiving element 5. Therefore, there is no need to dispose the light emitting element 4 inside the cylindrical code wheel 2a, and there is no need to dispose the light receiving element 56 outside the cylindrical code wheel 2a. The diameter dimension is reduced, and miniaturization can be achieved.

[Effects of the Invention] As described above, the present invention includes a code wheel made of a transparent cylindrical body with a large number of rotating slits formed on the circumferential surface, which is attached externally to a rotating shaft, and a V-shaped groove is formed on one end surface of the code wheel. is bored in the rotational direction, a reflective surface is formed on the side surface of the rotating shaft of the V-shaped groove, a half-mirror surface is formed on the outer surface, and an appropriate number of fixing slits are formed facing the outer peripheral surface of the code wheel. A reflective type 7-axis beam (V-) is arranged, and the light emitting element is arranged so as to project light approximately parallel to the axial direction, and the light reflected in the radial direction by the above-mentioned reflecting surface and transmitted through the half mirror surface. The light-receiving element is arranged so as to receive the light that is interrupted by both slits and is reflected on the back surface of the half mirror surface, which is approximately parallel to the axial direction.Since a cylindrical code wheel is used, the axial It is possible to prevent problems caused by loads being applied in the direction, and also to emit light in the axial direction from the light projecting element, and reflect this light in the radial direction by the reflective surface, so that the light is interrupted by both thrusts. Since the light is reflected by a half mirror and received by the light receiving element, there is no need to place the light emitting element inside the cylindrical code wheel, and there is no need to place the light receiving element outside the cylindrical code wheel. This has the effect of reducing the size by reducing the outer diameter.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the schematic configuration of one embodiment of the present invention;
The figure shows a schematic configuration of a conventional example, FIGS. 3(a) and 3(b) are front views of the same essential parts, and FIG. 4 is a diagram showing a schematic configuration of another conventional example. 1... Rotating shaft, 2a... Code wheel, 3a...
・Phase plate, 4... Emitter element, 5... Light receiving element, 6... Bush, 7... V-shaped groove, 8... Reflective surface, 9... -7 mirror surface .

Claims (1)

[Claims] (1) A code wheel made of a transparent cylindrical body with many rotating slits formed on the circumferential surface is attached externally to the rotating shaft, and a V-shaped groove is bored in the rotational direction on one end surface of the code wheel. A reflective surface is formed on the side surface of the rotating wheel of the groove, a half mirror surface is formed on the outer surface, and a reflective phase plate with an appropriate number of fixed slits is arranged opposite to the outer peripheral surface of the code wheel. The light emitting element is arranged so as to emit light approximately parallel to the axial direction, and the light reflected in the radial direction by the reflecting surface and transmitted through the half mirror surface is interrupted by both slits, and the light is transmitted to the back surface of the half mirror surface. An optical rotary encoder characterized in that a light-receiving element is arranged so as to receive light that is substantially parallel to an axial direction and is reflected by an optical rotary encoder.