JPS62294908A - Optical rotary encoder - Google Patents

Abstract

PURPOSE:To prevent trouble due to load in a shaft direction and to achieve miniaturization, by providing a light receiving element reflecting the light emitted from a light emitting element arranged so as to emit light parallel to the shaft direction and receiving the reflected light through both slits. CONSTITUTION:A light emitting element 4 is arranged so as to emit light parallel to a shaft direction 1 and the light emitted from the light emitting element 4 is reflected in the diameter direction of a bush 6 by the reflecting surface 7 formed to the peripheral surface of the bush 6 and this reflected light is received by a light emitting element 5 through both slits 10, 11. Since the peripheral surface of the bush 6 has a curvature and the light from the light emitting element 4 is reflected radially if light receiving elements 5a, 5b are arranged in two directions and the spacial positions of the fixed slits of the phase plates corresponding to both light receiving elements are shifted by 90 deg., two kinds of rotation detection signals having phase difference of 90 deg. are outputted and a direction of rotation is detected on the basis of both rotation detection signals. By this constitution, the simplification, miniaturization and cost reduction of constitution can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] 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 technology] Conventionally, in robots, machine tools (precepts, recorders, etc.),
This type of optical rotary encoder that performs position detection for measurement and feedback control is shown in Fig. 5 and f: tS6.
As shown in the figure, a flat code wheel 2 is attached to a rotating shaft 1.
A phase plate 3 is arranged to face the code wheel 2 with a slight gap, and light emitting cables 4 and 17, such as light emitting diodes, are mounted on both sides of the code wheel 2 and the phase plate 3. The light receiving elements 5 such as transistors and solar cells are arranged.

Here, the code wheel 2 is formed by drilling a large number of rotary slits 10 at equal intervals around the circumference of a disc, as shown in FIG. ) As shown in ), it is formed by drilling an appropriate number of fixed slits 11 in a fan-shaped plate, and when both slits ) 10 and 11 match, the light from the light emitting element 4 is received by the light receiving element 5. 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 may be displaced and the hood wheel 2 may come into contact with the second plate 3, or the code wheel 2 may be damaged. There was a problem that Therefore, in order to eliminate such inconveniences, as shown in FIG. An arc-shaped 7-Ace plate (3m) with an appropriate number of fixed slits 11 is arranged opposite to the outer circumferential surface of the code wheel 2a, and the light emitted and received through both slits io and 1i is There is one in which the rotation angle of the rotating shaft 1 is detected based on the change. 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 phase plate 3a interposed therebetween. In such a conventional example, even if an axial load is applied, there is no fear that the code wheel 2a and the 7A spray 3a will come into contact with each other (and the above-mentioned disadvantages due to an axial load can be prevented). However, since the light emitting element 4 and the light receiving element 5 are arranged in a straight line in the radial direction, and it is necessary to provide a space for the light emitting element 4 inside the code wheel 2a, the outer diameter dimension of the code wheel 2a There was a problem in that it became too large to be miniaturized.

[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 application of load in the axial direction, and to reduce the outer diameter of the code wheel. To provide an optical rotary encoder that can be easily miniaturized by reducing dimensions.

[Disclosure of the Invention] (Embodiment 1) Figs. 1 and 2 show an embodiment of the present invention, in which a code wheel 2a having a bottomed cylindrical shape and having a large number of rotating slits 10 formed on its circumferential surface is shown. The center of the bottom surface is attached to the rotating shaft 1, and a 7A spray plate 3a in which an appropriate number of fixing slits 11 are bored is arranged opposite to the outer peripheral surface of the code wheel 2a,
In an optical rotary encoder similar to the conventional example shown in FIG. The light emitting element 4 is arranged so as to emit light, and a truncated conical bush 6 having a reflective surface 7 formed on the circumference that reflects the light emitted from the light emitting element 4 in the desired direction is used to form a hood. The wheel 2a is attached to the rotating shaft 1, and the light receiving element 5 is arranged at a position where the light reflected by the reflecting surface 7 is received through both the slits. The reflective surface 7 has a straight line shape as shown in FIG. 2(a), but as shown in FIG. 2(b), the bush 6
The operation of the embodiment will be described below by forming the circumferential surface of the reflecting surface 7 into a concave shape. Now, the light emitting element 4 is arranged so as to emit light substantially parallel to the axial direction 1, and the light emitted from the light emitting element 4 is reflected by the reflective surface formed on the circumferential surface of the bushing 6. 7, and this reflected light is received by the light receiving element 5 via both the slits 10 and 11. Here, the surface of the bushing 6 has a curvature, and the light from the light projecting element 4 is reflected radially, so as shown in Figure v43,
The light receiving elements 5a and 5b are arranged in the direction, and both light receiving elements 5g
, 5b, if the spatial phase of the fixed slit of the phase plate (not shown) is shifted by 90°, then 90
Two types of rotation detection signals with a phase difference of Since it does not require a special reflecting mirror or the like, the number of parts does not increase, and the structure can be simplified and costs can be reduced.

On the other hand, if the peripheral part of the bushing 6 is formed into a concave shape as shown in FIG. It will be done.

(Example 2) PIS 4 shows still another example, in which the code wheel 2b and the rotating shaft 1 are integrally molded with transparent resin, and the bushing part 6° where the reflective surface 7 is formed is formed. A metal thin film is deposited on the circumferential surface and the slit portion of the outer circumferential surface where the rotating slit 10 is formed, and the rotating slit 10 is formed by etching on the slit portion, which simplifies the structure and reduces costs. This allows it to be made cheaper.

[Effects of the Invention] As described above, the present invention includes a code wheel having a cylindrical shape with a bottom and a plurality of rotating slits on the circumferential surface, the center of the bottom surface of which is attached to the rotating shaft, and the outer circumferential surface of the code wheel In an optical rotary encoder, phase plates with an appropriate number of fixed slits are placed facing each other, and the rotation angle of the rotating shaft is detected by changes in the light emitted and received through both slits. , a truncated conical bush in which a light emitting element is arranged so as to emit light approximately parallel to the axial direction, and a reflective surface is formed on the circumferential surface to reflect the light emitted from the light emitting element in the radial direction. The code wheel is attached to the rotating shaft, and the light receiving element is placed at a position where the light reflected by the reflecting surface is received through both slits.Since the cylindrical code wheel is used, the shaft In addition, since the light emitting element emits light in the axial direction, and the light is reflected in the radial direction by the reflective surface, the light emitting element can be shaped like a cylinder. There is no need to arrange it inside the shaped code wheel, and the outer diameter can be reduced, resulting in more compact size.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the schematic configuration of one embodiment of the present invention;
Figures (a) and (b) are the same main parts as above, an lfr side view, Figure 3 is a diagram showing the schematic configuration of another embodiment, Figure 4 is a sectional view of the main parts of another embodiment, and tjS5 is a A diagram showing the schematic configuration of the conventional example, tIS6 diagrams (a) and (b) are front views of the main parts of the same as above, tl
FIG. S7 is a diagram showing a schematic configuration of another conventional example. 1... Rotating shaft, 2a, 2b... Code wheel, 3
a... Phase plate, 4... Light emitting element, 5...
- Light receiving element, 6... Bush, 7... Reflective surface. Agent Patent Attorney Ishi 1) Ai Figure 7, Figure 4, Figure 5

Claims (2)

[Claims] (1) A bottomed cylindrical code wheel with a large number of rotating slits on its circumference is attached to the rotating shaft at the center of its bottom surface, and an appropriate number of fixed slits are formed opposite the outer circumferential surface of the code wheel. In an optical rotary encoder in which a perforated phase plate is arranged and the rotation angle of the rotation axis is detected by changes in light emitted and received through both slits,
The light emitting element is arranged so as to emit light approximately parallel to the axial direction, and the bush is shaped like a truncated cone and has a reflective surface on its circumference that reflects the light emitted from the light emitting element in the radial direction. 1. An optical rotary encoder characterized in that a code wheel is attached to a rotating shaft, and a light receiving element is arranged at a position where light reflected by the reflecting surface is received through both slits. (2) The optical rotary encoder according to claim 1, wherein the bushing has a concave circumferential surface to impart a light condensing function to the reflective surface.