JPS5829849B2 - rotary encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary encoder, more specifically, a desired angle θ.
This relates to a rotary encoder that generates sin θ, cos θ, or a number of pulses proportional to θ by rotating it, and is used, for example, in planimeters, drawing instruments, and the like.

As a conventional device of this type, for example, the present inventor has applied for Patent No. 48-134134, but in this conventional device, the second scale plate is moved parallel to the fixed first scale plate. The scale plate of No. 1 is large, and it is necessary to form a scale line with a width of 25μ on this scale plate in order to improve measurement accuracy, but the line is thin and the area of the scale plate is large, so it is expensive. Ta.

The present invention solves this problem by providing a pair of first and second scale plates so as to rotate at equal angles in the same direction, and having parallel scale lines on the first and second scale plates. The rotation angle of the scale plate is detected as a pulse by interfering with a part of the scale plate.

An embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIGS. 1 and 2, a pair of first and second shafts 2 and 3 are supported in the housing 1 so as to be vertically rotatable by bearings 4 and 4 pivots 5° and 6.7, respectively. 3 are connected via gears 8, 9 and an intermediate gear 11 fixed to a shaft 10, and are connected so as to rotate at equal angles in the same direction.

When the present invention is applied to a planimeter, linear wheels 12 and 13 are fixed to both sides of the housing 1, and a measuring rod 14 for tracing a figure is fixed to the upper end of the shaft 2.

Shafts 2 and 3 are pulleys or belts instead of intermediate gears,
They may be connected by a wire or the like so that they rotate at equal angles in the same direction.

In FIG. 3, 15 is a frame that supports the shaft 10 of the intermediate gear 11, and 16 and 17 are the same pivots.

As shown in the second and fourth figures, the shafts 2 and 3 are made of glass, for example.
The first and second scale plates 20 and 21 made of a transparent material such as plastic are fixed, and the first and second scale plates 20 and 21 are fixed.
Parallel scale lines 23 and 24 are provided at positions overlapping each other on the outer periphery as shown in the fourth figure.

A vernier scale line 23a having a phase difference with respect to the scale line 23 is further provided on the inner periphery of the first scale plate 20.

As shown in the third figure, a lens 25 and a light source 26 are fixed by a frame 21 below the weight portions of the first and second scale plates 20 and 21, and a pair of phototransistors 28 and 29 are fixed above them. It is fixed by a frame 30, and a light shielding plate 31 is fixed between the phototransistors 28 and 29.

Since the present invention has such a configuration, when the shaft 2 rotates by an angle θ, the shaft 3 also rotates by the same angle in the same direction.

Therefore, the overlapping parts of the scale plates 20 and 21 operate at the same angle in opposite directions as shown by the arrows in FIG. moves relatively by a length proportional to 2 sin θ.

Therefore, the scale line 23 is passed through the lens 25 from the light source 26.
Moiré interference fringes proportional to 2 sin θ are generated in the light passing through 23a and 24, and the phototransistor 28 2
9, a number of pulses proportional to 2 sin θ are generated.

In the above embodiment, the diameters of the first and second scale plates 20.degree. 21 are equal, but they do not necessarily have to be equal.

At this time, the overlapping portions of the two actuate each other at a magnification of 2 sin θ or more.

As described above, in the present invention, since the overlapping portions of the first and second scale plates operate in opposite directions, 2 sin
Since it operates at a magnification of θ or higher, it is possible to generate pulses proportional to sin θ with an accuracy more than twice that of conventional ones, making it possible not only to perform precise measurements, but also to increase the size of the scale lines to, for example, 50μ. Therefore, scale lines can be formed at low cost, and the device can also be made smaller.

5 to 8 show other embodiments of the present invention, in which sin
It is designed to generate pulses proportional not only to θ but also to cos θ.

That is, the third shaft 35 is provided at a position offset from the shaft 2 in a perpendicular direction with respect to the first shaft 3, and this shaft 35 is connected to the gear 36,
A third scale plate 37 is fixed to the shaft 35 and connected to the shaft 3 through an intermediate gear 11a so as to rotate in the same direction and at the same angle. A scale line 38.38a similar to 20 is provided, and the second and third scale plates 2
A light source 34 and a lens 39 are provided below the 1.degree. 37 overlap, and a phototransistor 40.degree. 41 is provided above them.

In this case, when the shaft 2 rotates by the rotation angle θ, the scale line 38°38a
and 24 are always parallel and move relative to each other by a length proportional to 2 cos θ (strictly speaking, not cos θ (1-cos θ)), and the light passing through that part has moiré interference fringes proportional to 2 cos θ. is generated, and the phototransistor 40
, 41, a number of pulses proportional to 2 cos θ are generated, and like s1n θ, cos θ can also be measured with more than twice the accuracy.

In the above example, the scale lines 23, 23a, 24 are provided in parallel, that is, in the direction connecting the axes 2.3 of the first and second scale plates 20.21, but they may be provided in the radial direction.

In that case, it becomes an encoder that generates pulses proportional to the rotation angle θ.

[Brief explanation of the drawing]

Fig. 1 is a plan view of one embodiment of the present invention, and Fig. 2 is its A-
3 is a sectional view taken along line B-B, FIG. 4 is an enlarged explanatory plan view of the scale plate, FIG. 5 is a plan view of another embodiment of the present invention, and FIG. 6 is its sectional view. FIG. 1 is a cross-sectional view taken along line C--C, FIG. 1 is a cross-sectional view taken along line D--D, and FIG. 8 is an enlarged explanatory plan view of the scale plate. 20.21...Scale plate, 23,24...
・Scale line.

Claims (1)

[Claims] A pair of first and second scale plates are provided so as to rotate at equal angles in the same direction, parallel scale lines are provided on the periphery of the first and second scale plates, and the peripheries are made to interfere with each other. ,
A rotary encoder characterized in that moiré fringes are detected by operating the peripheral portions of the pair of scale plates in opposite directions, and the rotation angle of the scale plates is detected as a pulse.