JPH02128117A - Optical rotary encoder - Google Patents

Abstract

PURPOSE:To enable a reduction in the number of stock parts with an easier inventory control by arranging types of slit windows comprising slit windows with different pitches in a circumferential direction of an index scale, which is fixed directly on a housing. CONSTITUTION:Index scale 6 formed in a disc are fastened directly on a housing 4 through ball bearings 2 and 3, eventually allowing the elimination of a mounting base. The scales 6 are provided with group of slit windows comprising a number of slit windows different in pitch and width therebetween and identical in the same group at the same position radially relative to one another and formed separately in sectors circumferentially at eight points. In the assembling, one of the slit window groups provided on the scale 6 to match slit windows provided on a main scale 5 with desired resolutions and the slit window group thus selected is arranged on an optical axis of a light emitting element 8 and a photo detector 9. Thus, one type of scales can be used for a rotary encoder provided with various resolutions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical rotary encoder used for detecting the rotation speed and rotation angle of a servo motor or the like.

[Prior Art] Fig. 3 is a longitudinal sectional view of a conventional optical rotary encoder as described above, and Figs. 4 and 5 are side views of the main scale and index scale of the encoder shown in Fig. 3. .

In FIG. 3, reference numeral 1 denotes a rotating shaft, and the rotating shaft 1 is rotatably supported by a hanging 4 through ball bearings 2 and 3. 5 is the main scale; main scale 5 is
As shown in FIG. 4, a chromium film is deposited on a glass plate, and in order to obtain the desired resolution, slit windows 5a with the necessary pitch and width are etched radially around the entire circumference. A slit circular band 5b is formed by etching on the outer circumferential side thereof concentrically with these. 6 is a rectangular index scale, and the index scale 6 has a chromium film deposited on a glass plate, as shown in FIG. A slot window group consisting of one type of slit window 6a is opened by etching at a position corresponding to the radial position, and the index scale 6 is glued to the mounting base 7.
is fixed to the housing 4. 8 is a light emitting element;
Reference numeral 9 denotes a light receiving element, and these elements 8.9 are arranged facing each other outwardly on both sides of the main scale 5 and index scale 6, the light emitting element 8 is fixed to the housing 4, and the light receiving element 9 is fixed to the printed board. vi 10 , a waveform shaping circuit 11 is fixed to this substrate 10 , and these are fixed to the housing 4 . Reference numeral 12 denotes a cover attached to the outer periphery of the housing 4 to cover each of the above-mentioned members.

Next, the operation of this optical rotary encoder will be explained.

When the power is turned on and the light emitting element 8 emits light, the light passes through the group of slit windows 6a of the index scale 5, then passes through the slit window 5a of the main scale 5, and irradiates the light receiving element 9. At this time, the light receiving element 9 generates a current proportional to the amount of light. Here, when the rotation shaft 1 rotates, the light emitted from the light emitting element 8 repeatedly passes through and is blocked by the slit window 5a of the main scale 5, and the light emitting current of the light receiving element 9 becomes a pseudo sine wave. The index scale 6 cuts the oblique incident light emitted from the light emitting element 8 and allows only the effective parallel component light to pass through, thereby increasing the peak value of the light emitting current. This current is converted into a voltage by a waveform shaping circuit 11, shaped into a pulse waveform, and output to the outside.

Also, if the slit window 5a of the main scale 5 and the slit window 6a group of the index scale 6 are not aligned with high precision, the peak value of the current will decrease. I move it slightly to align it. Furthermore, by correcting the run-out of the slit window band 5b of the main scale 5 with the ball bearings 2 and 3 as the rotation reference, the jitter amount of the pulse waveform is reduced. It takes time to align the slit windows 6a of the index scale 6 and the slit windows 6a of the index scale 6, and the workability is not good. In addition, since the pitch and width of the slit windows that make up the slit window group are constant, it is not possible to support optical rotary encoders with various resolutions, inventory management is complicated, and the mounting base 7 is Since it is necessary, there is a problem in that the price is also high.

This invention was made to solve the above-mentioned problems, and by improving the index scale, it facilitates the alignment work between the slit window of the main scale and the slit window group of the index scale. The objective is to obtain an optical rotary encoder that supports a wide range of resolutions with an index scale, eliminates the complexity of inventory management, eliminates the need for a mounting base, reduces the number of parts, and lowers the price. There is.

[Means for Solving the Problems] The optical rotary encoder according to the present invention has an index scale formed into a disk shape, and a plurality of types of slit window groups in the circumferential direction of the scale, and slits between the groups. The windows are arranged at different pitches and the index scale is directly fixed to the housing.

[Function] In the optical low-resolution encoder of the present invention, one type of slit window group provided on the index scale is selected in accordance with the slit window provided on the main scale of desired resolution at the time of assembly, and this slit window By arranging the group on the optical axis of the light emitting element and the light receiving element, one type of index scale can be used in optical rotary encoders with many types of resolution. Further, the alignment work between the index scale and the main scale may be performed by correcting or removing rotational runout between the main scale and the index scale. Furthermore, since the index scale is directly fixed to the housing, the conventional mounting base can be eliminated.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of the optical rotary encoder according to this embodiment, and FIG. 2 is a side view of the index scale of the encoder shown in FIG. 1. In Figures 1 and 2, 1 is the rotating shaft, 2 and 3 are ball bearings, 5 is the main scale,
8 is a light emitting element, 9 is a light receiving element, 10 is a printed circuit board, 1
1 is a waveform shaping circuit, 12 is a cover, and these are the third
The structure is similar to the conventional optical rotary encoder shown in FIGS.

In this embodiment, the index scale 6 is formed in the shape of a disk, and is directly fixed by adhesive or the like to the housing 4 supporting the rotary shaft 1 via a ball bearing 2.3. Also, on index scale 6,
Slit window groups consisting of a large number of slit windows 6a to 6h, which have different pitches and widths between groups but are the same within the same group, are provided at the same position in the radial direction, and are arranged at eight locations in the circumferential direction. The slit windows 6a to 6h are each formed in a fan shape with mutual intervals, and a slit circular band 61 is disposed concentrically on the outer peripheral side of the group of slit windows 6a to 6h. The configuration of the housing 4 and index scale 6 other than the above is shown in FIG.

This is similar to the conventional one shown in FIG.

Further, the operation of the encoder according to this embodiment is similar to that of the conventional encoder shown in FIGS. 3 to 5.

When assembling the optical rotary encoder of this embodiment, the slit windows 6a to 6 of the index scale 6 corresponding to the slit windows of the main scale 5 having the desired resolution are
One of group h is selected and placed on the optical axis of the light emitting element 8 and the light receiving element. In addition, to align the index scale 6 and the main scale 5, temporarily fix the index scale 6 to the housing 4, keep the rotating shaft 1 stationary, and rotate the index scale 6 using the ball bearing 2.3 as a rotation reference. , the index scale 6 is slightly moved in the radial direction to correct and eliminate rotational vibration of the slit circular band 61. Next, the main scale 5 is temporarily fixed to the rotating shaft 1, the housing 4 is kept stationary, the main scale 5 is rotated using the ball bearing 2°3 as a rotation reference, and the main scale 5 is slightly moved in the radial direction to form a slit circle. To eliminate rotational runout of the band 5b.

In the index scale 6 of the above embodiment, one track is provided with eight types of slit window groups 6a to 6h, but the index scale of the present invention may have any number of slit window groups as long as it is plural. Further, in this invention, the slit window group of the index scale may be divided into several groups, and the positional relationship of each group may be shifted. Furthermore, although the outermost circular band of the index scale is a slit circular band, it is possible to Alternatively, a chromium-deposited circular band may be provided on the glass part (or, furthermore, the number of slit window groups may be increased and the outer edges of these slit window groups may be used in place of the slit circular band). The same effects as those of the embodiment are achieved.

[Effects of the Invention] As explained above, according to the present invention, the index scale is made into a disk shape, and the plurality of types of slit window groups each consisting of slit windows with different pitches are arranged as described above to correspond to the plurality of types of resolution. The index scale was arranged in the F [direction, and this scale was fixed directly to the housing, so
One type of index scale can be used with optical low-resolution encoders with many types of resolution, making inventory management easier.Also, alignment work can be done by adjusting the main scale and index scale instead of correcting it by looking at the voltage output. This can be done simply by correcting and removing the rotational runout, and the index scale mount can be eliminated, and the number of parts can be reduced, which has the effect of lowering the price.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of an optical rotary encoder according to an embodiment of the present invention, FIG. 2 is a side view of the same index scale, FIG. 3 is a vertical sectional view of a conventional optical rotary encoder, and FIG. The figure is a side view of the main scale, and FIG. 5 is a side view of the index scale. DESCRIPTION OF SYMBOLS 1... Rotating shaft, 2, 3... Ball bearing, 4... Housing, 5... Main scale, 5a... Slit window, 5b... Slit circular band, 6... Index scale , 6a to 6h... slit window, 61... slit circular band, 8... light emitting element, 9... light receiving element. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A main scale fixed to the rotating shaft, an index scale fixed to the housing facing the main scale, and a light emitting element and a light receiving element arranged opposite to each other on both sides of the main scale and index scale. In the optical rotary encoder, the index scale is formed into a disk shape, and a plurality of types of slit window groups are formed in the circumferential direction of the index scale, and the pitches of the slit windows between the groups are made different from each other. An optical rotary encoder characterized in that the index scale is directly fixed to the housing.