JPH0615976B2 - Method of manufacturing rotary encoder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a rotary encoder, and in particular, a photoelectric rotary encoder that detects a rotation amount and a rotation direction based on a change in information obtained according to the rotation of a code plate. Regarding the method.

(Prior Art) An optical rotary encoder outputs a pulse train according to a rotation angle by rotating an input rotation shaft as is well known, and both sides of a code plate (rotation slit plate) provided with light and dark are provided. By arranging the light emitting and light receiving elements facing each other, it is possible to detect the change in the light amount due to the rotation of the code plate.

FIG. 5 shows the basic principle of the above-mentioned optical rotary encoder.

That is, the light emitting / receiving elements 3 and 4 arranged to face each other.
A code plate 2 is provided in between, and the rotary shaft 1 is attached to the code plate 2.
A slit corresponding to the number of pulses per one rotation is formed, and when the rotating shaft 1 is connected to a shaft whose rotational displacement is to be measured by a coupling or the like and rotated, the slit shields and transmits light. As a result, an increase or decrease in current occurs in the light receiving element 4. In this case, the code plate 2 and the light receiving element 4
A fixed slit plate 10 is provided between and in order to improve the S / N. Then, the change in the current is converted into a pulse signal by the voltage comparison circuit 13, and two sets of signals (A phase, B phase) having different phases are output through the output circuit 14.

By the way, the light flux from the light emitting element 3 is not ideally a parallel light flux, but is actually a radial light flux as shown in FIG. 6, and in addition, the fixed slit plate is used so as to increase the amount of light to be transmitted. Since a plurality of slits corresponding to the size of the light receiving element 4 are formed in the light receiving element 10, leak light is generated due to the reflection of light even when the code plate 2 shields the light.

Therefore, in order to reduce these leaked light as much as possible, conventionally, as shown in FIG. 7, the distance (gap G) between the code plate 2 and the fixed slit plate 10 has been reduced.

(Problems to be Solved by the Invention) However, the above-described gear gap G between the code plate 2 and the fixed slit plate 10 depends on the stacking of the dimensional tolerances of the respective components, and, for example, in the case of FIG. G is G = a + b + c-d-e where a is the housing size b is the thickness of the fixed slit plate c is the difference in the width of the bearing (including the gap due to preload) d is the width of the bearing e is the boss It becomes the dimension.

It should be noted that FIG. 8 described above is an example in which the structure is considerably simplified, and in some cases, the a dimension is divided into two or three parts, and an adjustment spacer is inserted between them to obtain a predetermined gap G. There is also.

That is, in the case of the above equation, each part had to be machined to the accuracy of the predetermined standard so that the predetermined gap G was obtained in a state where the five constituent parts were assembled.

In this case, as the number of pulses per rotation increases,
If the code plates 2 have the same outer shape, the pitch of the slits becomes small, and the gap G must be made small accordingly. For this reason, it is necessary to make the component accuracy even more severe.

By the way, if the ground of the gap G per rotation changes,
This change leads to an increase / decrease in the amount of leaked light, which in turn causes an increase / decrease in photocurrent, which adversely affects the output signal. The influence of this can be reduced as much as possible by improving the electric circuit and the detection means, but in any case, it is preferable that the amount of change in the gap G is small.

On the other hand, if the precision of the parts is made strict, the number of processing steps is increased, and the number of steps is reduced, so that the cost is increased as a whole.

The present invention has been made to solve the above problems,
The purpose of this is to perform post-processing after assembling the parts so that the accuracy of the necessary parts can be increased at low cost without improving the processing accuracy of the individual components, and by extension, the rotary encoder having high resolution. It is to provide a manufacturing method of.

(Means for Solving the Problem) In order to achieve the above-mentioned object, the method of the present invention is such that light-emitting / light-receiving elements are arranged opposite to each other on both front and back sides of a code plate attached to a rotary shaft, and the code plate is rotated according to the rotation of the code plate. In a method of manufacturing a rotary encoder that detects the amount of rotation and the direction of rotation of a rotary shaft by a detection signal obtained from the above, the rotary shaft is supported by a bearing provided in a housing, and a code plate is attached to one end of the rotary shaft. A boss is attached to form a climate unit assembly, and then the housing in this mechanism unit assembly is chucked and fixed, and the rotary shaft is in contact with a stopper on the end face of the shaft so that the rotary shaft does not displace in the axial direction. Is chucked by a flexible chuck, and the code plate mounting surface of the boss is machined while rotating the rotary shaft.

(Operation) With the above-described structure, in the method of the present invention, as shown in FIG. 2, the rotary shaft 1 is supported via the bearings 6a and 6b, and one end of the rotary shaft 1 is provided with the boss 7 for attaching the code plate. Is provided to form a mechanical assembly 15. At this time,
The dimension e from the bearing contact surface of the boss 7 to the code plate mounting surface (hereinafter referred to as the Y surface) is preliminarily processed to be large. Therefore, if the code plate 2 is assembled in this state, the gap G becomes large and the performance as an encoder cannot be sufficiently exhibited.

Next, the mechanism assembly (subassembly) 15 assembled as described above is set in a dedicated processing machine, and the gap G
Is processed to obtain a predetermined value. At this time, the housing 5 is chucked and fixed in advance, and the rotary shaft 1 is chucked by a flexible chuck with a stopper abutting against one end of the shaft so that the rotary shaft 1 is not displaced in the axial direction. When the rotary shaft 1 is rotated, Y of the boss 7
The surface is processed.

Generally, when the rotary shaft 1 is rotated while being supported by the bearings 6a and 6b, the center of the bearing and the center of the rotary shaft do not coincide with each other, so that the Y-plane of the boss 7 is shaken. However, if the Y-axis is processed while chucking the rotating shaft 1 and rotating the rotating shaft 1 as described above, it is possible to eliminate the wobbling of the Y-plane even if there is a misalignment of the shaft center. The gap G can be obtained.

(Examples) Hereinafter, preferred examples of the method of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic structure of a rotary encoder obtained according to the present invention, and FIGS. 2 to 4 show an embodiment of the method of the present invention.

In FIG. 1, a bearing 6 is provided in the approximate center of the housing.
a, 6b are provided, the rotary shaft 1 is supported by the bearings 6a, 6b, and a boss 7 for mounting the code plate 2 is provided at one end of the rotary shaft 1. Further, the light emitting element 3 and the light receiving element 4 mounted on the substrates 8 and 9 are arranged to face each other on both front and back sides of the code plate 2, and the code plate 2 is further provided.
A fixed slit plate 10 for improving the S / N ratio is provided between and the light receiving element 4. A cover 11 for covering these is attached to the outer peripheral portion of the light emitting side substrate 8, and a cable 12 for signal input / output is led out from the substrate 8.

Here, in the patent of the present invention, first, the rotary shaft 1 is supported by the bearings 6a and 6b provided in the housing 5, and the boss 7 for mounting the code plate is attached to one end of the rotary shaft 1. This is a partial assembly.

That is, in FIG. 2, the rotary shaft 1 is supported by bearings 6a and 6b provided at the substantially center of the housing 5, and one end of the rotary shaft 1 is provided with a boss 7 for attaching the code plate.
Is provided to form a mechanical assembly 15. The rotary shaft 1 is composed of a straight rod provided with a flange 18 near one end and a threaded portion 19 formed on the other side. Further, the flange 18 is brought into contact with the inner race of the bearing 6b, the boss 7 for attaching the code plate is screwed into the screw portion 19, and the end face of the boss 7 is brought into contact with the inner race of the bearing 6a. There is.

The boss 7 is formed in advance so that the dimension e from the contact surface with the bearing 6a to the code plate mounting surface (Y surface) is large. For this reason, if the code plate 2 is attached to the Y surface as it is, the gap G becomes large and the function as an encoder cannot be sufficiently exerted.

On the side of the housing 5 to which the boss 7 is attached, a concave portion 16 for accommodating the light receiving element 4 and an attaching surface (hereinafter referred to as X surface) for attaching the fixed slit plate 10 are formed above the concave portion 16. .

Next, in the present invention, the housing 5 in the mechanical assembly 15 is chucked and fixed, and the rotary shaft 1 is attached with a stopper abutting against the end face of the rotary shaft 1 so as not to cause axial displacement. It is characterized in that it is chucked by a flexible chuck and the code plate mounting surface of the boss 7 is processed while rotating the rotary shaft 1.

In this embodiment, as shown in FIG. 3, the housing 5 is chucked and fixed by the chuck 20 on the processing machine side, and the rotary shaft 1 is prevented from being displaced in the axial direction.
The rotary shaft 1 is chucked by the flexible chuck 22 in a state where the stopper 21 is in contact with the left end surface of the rotary shaft 1.

That is, the flexible chuck 22 has a chuck portion 23 having a flexible joint formed at one end (on the side where the rotary shaft 1 is gripped), a pulley portion 24 at the other end, and a central portion thereof is rotated by a bearing 25. A through hole 26 for supporting the stopper 21 is inserted in the center portion in the longitudinal direction.
Are formed. The screw 27 is for fixing the stopper 21.

The rotation is transmitted from the motor 29 side to the pulley portion 24 via the belt 28, and at this time, the rotary shaft 1 is operated by the action of the flexible chuck 22 and the flexible joint.
Even if there is some misalignment between and, it can be absorbed and smooth rotation can be transmitted. In this way, the Y surface of the boss 7 is cut by the cutting tool 30 while rotating the rotary shaft 1.

FIG. 4 shows another embodiment of the present invention.

In the above-described embodiment, the case where the Y surface is processed by using the turning tool 30 by the lathe has been described. However, these processings can also be performed by a polishing machine or a milling machine. In this embodiment, an example of processing by the polishing machine is shown. Has been done.

That is, the housing 5 is chucked and fixed as described above, and the rotary shaft 1 is chucked by the flexible chuck 22 and then rotated. Then, the Y surface of the boss 7 is ground by the grindstone 31a or 31b which rotates in the A direction or the B direction.

In each of the above embodiments, for example, it is possible to simply attach the rotary shaft 1 to a lathe or the like and machine the Y surface of the boss 7. However, this is the bearing on the boss 7.
Although the dimension e from the contact surface with 6a to the Y surface can be obtained, the performance as an encoder cannot be sufficiently exerted for the following reasons.

That is, when the bearings 6a and 6b are fitted to the housing 5, a gap or eccentricity may occur between the housing 5 and the bearings 6a and 6b due to variations in component accuracy, and the bearings 6a and 6b may have the rotating shaft 1 When the bearing is inserted and supported, the rotary shaft 1 may be bent due to the above-mentioned clearance or the like. Furthermore, since the fixed slit plate 10 is attached to the X plane, the X plane and the rotating Y plane must be parallel. Furthermore, in many cases, the center of the housing 5 and the bearings 6a, 6b and the center of the rotary shaft 1 do not coincide.

Further, as described above, if the rotating shaft 1 is simply chucked and the Y surface is machined, a shake occurs on the Y surface when the shaft rotates,
This swing causes the gap G to change.

Therefore, in this embodiment, even if there is a deviation in the shaft center, the deflection of the Y surface is suppressed. Specifically, the housing 5 is fixed by the chuck 20, and
The shaft 1 is rotated by the flexible chuck 22 that rotates while the shaft core moves flexibly, and the bearings 6a, 6b are rotated.
To prevent the thrust load during cutting from being applied to the stopper 21
The post-processing of the mechanical assembly 15 is carried out while preventing the axial movement of the rotary shaft 1.

That is, according to the present embodiment, the Y surface of the boss 7 can be processed by rotating the bearings 6a, 6b and the rotating shaft 1 at the center thereof, not at the center of each of the bearings 6a, 6b and the rotating shaft 1. It is possible to obtain a Y surface without Further, according to the present embodiment, it is possible to finish an article having accuracy equivalent to that of a high precision component without using a high precision component.

(Effects of the Invention) As described above, the present invention manufactures a rotary encoder that detects the rotation amount and the rotation direction of the code plate by arranging the light emitting / receiving elements facing each other on both front and back sides of the code plate attached to the rotary shaft. In the method, the rotary shaft is supported by a bearing provided in a housing, and a boss for attaching a code plate is attached to one end of the rotary shaft to form a mechanical assembly, and then the housing in the mechanical assembly is chucked. The king is fixed and the rotary shaft is chucked by a flexible chuck with the stopper abutting against the end face of the shaft so that the rotary shaft does not displace in the axial direction. While rotating the rotary shaft, the code plate of the boss is rotated. By processing the mounting surface, post-processing after assembling the parts is necessary at a low cost without improving the processing accuracy of individual component parts. Can improve the accuracy of the parts, it is possible to obtain a rotary encoder having thus high resolution.

[Brief description of drawings]

1 is a sectional front view of a rotary encoder, FIG. 2 is a sectional front view of a mechanical assembly, FIG. 3 is a diagram showing a state in which the mechanical assembly is processed by a lathe, and FIG. 4 is the same mechanical assembly. FIG. 5 is a diagram showing a state in which a product is processed by a polishing plate, FIG. 5 is a principle explanatory diagram of a rotary encoder, FIGS. 6 and 7 are diagrams showing a positional relationship among a light source, a fixed slit plate, and a code plate, respectively. The figure is a diagram showing the relationship between the size of each component of the rotary encoder and the gap G. 1 ... Rotary axis, 2 ... Code plate 3 ... Light emitting element, 4 ... Light receiving element 5 ... Housing 6a, 6b ... Bearing 7 ... Boss, 10 ... Fixed slit plate 15 ... Mechanical assembly 20 …… Chuck, 21 …… Stopper 22 …… Flexible chuck

Claims (1)

[Claims] 1. A light-emitting / light-receiving element is arranged opposite to each other on both front and back sides of a code plate attached to a rotary shaft, and a rotation amount and a rotating direction of the rotary shaft are detected by a detection signal obtained in accordance with the rotation of the code plate. In the method of manufacturing a rotary echoda, the rotary shaft is supported by a bearing provided in a housing, and a boss for attaching a code plate is attached to one end of the rotary shaft to form a mechanical assembly, and then the mechanical assembly is assembled. The housing is fixed by chucking, and the rotary shaft is chucked with a flexible chuck while the stopper is in contact with the end face of the shaft so that the rotary shaft is not displaced in the axial direction. A method for manufacturing a rotary encoder, characterized in that the code plate mounting surface of the boss is processed.