CN114689094A

CN114689094A - Reflective optical encoder

Info

Publication number: CN114689094A
Application number: CN202110270232.9A
Authority: CN
Inventors: 李企桓; 黄信荣; 张瑞彬; 陈易呈
Original assignee: Industrial Technology Research Institute ITRI
Current assignee: Industrial Technology Research Institute ITRI
Priority date: 2020-12-29
Filing date: 2021-03-12
Publication date: 2022-07-01
Also published as: TW202225642A

Abstract

A reflective optical encoder includes a reflector, a light source and a sensing module. The reflector has a reflecting surface. The reflecting surface has a plurality of sub-regions arranged in an arrangement direction. The reflectivity of the subregions is repeatedly increased and decreased along the arrangement direction to form a periodic function. The light source is used for emitting light to irradiate the reflecting surface of the reflecting piece. The reflecting piece and the sensing module can rotate relative to each other or move in parallel along the arrangement direction. The sensing module is used for receiving the light reflected by the reflecting surface.

Description

Reflective optical encoder

Technical Field

The present invention relates to an encoder, and more particularly, to a reflective optical encoder.

Background

In the field of machining equipment such as machine tools, in order to control or detect relative movement and position between a machining tool and a workpiece, it is necessary to provide a drive device for driving the machining tool or a drive device for driving the workpiece with an optical encoder for measuring the position, distance of movement, or angle of the machining tool or the workpiece. In a conventional optical encoder, a reflective optical encoder is taken as an example, and includes an encoding disc or an encoding ruler, a light source and a light sensor. The coding disc or the coding ruler has light and dark stripes and can reflect light of the light source, and the light sensor senses the light reflected by the stripes of the coding disc or the coding ruler to judge the position, the moving distance or the moving angle of the processing tool or the workpiece.

However, after the light and dark stripes and the spacing of the code disc or the code ruler are narrow to a certain extent, the reflected light will generate the phenomenon of slit interference, which causes sensing errors and limits the precision. If the distance or angle of the movement of the processing tool or the workpiece is within the range of a single stripe, it is determined by mistake that the movement is not performed, i.e., the detected position is not changed, which may cause the processing line to fail to operate normally. When the workpiece or the processing tool is finer, erroneous judgment occurs more frequently. On the other hand, in order to be assembled and combined with the processing equipment, the reflective encoder usually needs to be miniaturized, which further compresses the volume of the code disc or the code scale, and may sacrifice the precision of the reflective encoder, so increasing the precision is the key point in the research and development of the reflective encoder at present.

Disclosure of Invention

In view of the above problems, the present invention provides a reflective optical encoder, which improves the precision of the reflective optical encoder by avoiding the occurrence of the slit interference.

An embodiment of the invention provides a reflective optical encoder, which includes a reflector, a light source, and a sensing module. The reflector has a reflecting surface. The reflecting surface has a plurality of sub-regions arranged in an arrangement direction. The reflectivity of the subregions is repeatedly increased and decreased along the arrangement direction to form a periodic function. The light source is used for emitting light to irradiate the reflecting surface of the reflecting piece. The reflecting piece and the sensing module can rotate relative to each other or move parallel to each other along the arrangement direction. The sensing module is used for receiving the light reflected by the reflecting surface.

According to the reflective optical encoder of an embodiment of the present invention, the reflectivity of the sub-regions of the reflective surface of the reflector repeatedly increases and decreases along an arrangement direction to form a periodic function, so that when the sensing module senses the reflectivity of the sub-regions corresponding to one period of the periodic function, the relative rotation or parallel movement of the reflector and the sensing module can be known according to the reflectivity. Further, even if the size or angle of the reflecting member corresponding to one period is narrow, the phenomenon of slit interference is not likely to occur. Therefore, the precision of the reflective optical encoder can be improved by narrowing the size or angle of the reflective member corresponding to one period.

The foregoing summary of the invention, as well as the following detailed description of the embodiments, is provided to illustrate and explain the principles and spirit of the invention, and to provide further explanation of the invention as claimed.

Drawings

FIG. 1 is a schematic top-view cross-sectional view of a reflective optical encoder according to an embodiment of the present invention.

Fig. 2 is a schematic view of the reflector of fig. 1.

FIG. 3 is an enlarged view of the reflector of FIG. 2, showing the reflector of the display portion in an enlarged view.

FIG. 4 is a schematic diagram of the sensing module of FIG. 1.

FIG. 5 is a schematic diagram illustrating the sensor assembly of FIG. 4 sensing the intensity of the light reflected by the reflective surface of FIG. 3.

Fig. 6 is a schematic cross-sectional view illustrating the reflector of fig. 2.

FIG. 7 is an enlarged schematic view of a reflector according to another embodiment of the invention, which enlarges the reflector of the display portion.

FIG. 8 is an enlarged schematic view of a reflector according to another embodiment of the invention, which enlarges the reflector of the display portion.

Fig. 9 is an enlarged schematic view of a reflector according to another embodiment of the invention, which enlarges the reflector of the display portion.

FIG. 10 is a schematic cross-sectional view of a reflective optical encoder according to another embodiment of the present invention.

Fig. 11 is a schematic view of the reflector of fig. 10.

FIG. 12 is an enlarged view of the reflector of FIG. 11 showing a portion of the reflector in an enlarged scale.

FIG. 13 is a diagram of the sensing module of FIG. 10.

Detailed Description

The detailed features and advantages of the embodiments of the present invention are described in detail below in the detailed description, which is sufficient for any person skilled in the art to understand the technical content of the embodiments of the present invention and to implement the embodiments, and the related objects and advantages can be easily understood by any person skilled in the art from the disclosure, claims and drawings of the present specification. The following examples further illustrate aspects of the present invention in detail, but are not intended to limit the scope of the invention in any way.

In the drawings, the size, proportion, angle, and the like of the drawings are exaggerated for the purpose of illustration, but the drawings are not intended to limit the present invention. Various modifications can be made without departing from the gist of the present invention. The top, bottom, front and back orientations mentioned in the description of the embodiments and the drawings are for illustration purposes and are not intended to limit the invention.

Please refer to fig. 1, fig. 2, fig. 3 and fig. 4. FIG. 1 is a schematic top view, cross-sectional view, illustrating a reflective optical encoder according to an embodiment of the present invention. Fig. 2 is a schematic view of the reflector of fig. 1. Fig. 3 is a partially enlarged view of the reflector of fig. 2. FIG. 4 is a diagram of the sensing module of FIG. 1. A reflective optical encoder 1 according to an embodiment of the present invention is described below.

As shown in fig. 1, in the present embodiment, the reflective optical encoder 1 includes a reflector 11, a light source 12, a sensing module 13, a circuit board 14 and a plurality of moving parts 15. The reflector 11 has a reflective surface 110. The light source 12 is used for emitting a light ray E1 to illuminate the reflecting surface 110 of the reflector 11. The sensing module 13 has a sensing surface 130 facing the reflector 11. The sensing surface 130 of the sensing module 13 is used for receiving a light ray E2 reflected by the reflecting surface 110. The light source 12 and the sensing module 13 are disposed on the circuit board 14. The reflective element 11 is fixed and does not move, and the circuit board 14 can move parallel to the reflective element 11 along an arrangement direction S1 by the moving element 15, so that the reflective element 11 and the sensing module 13 can move parallel to each other along the arrangement direction S1, but not limited thereto. In other embodiments, the light source 12 may be disposed around the reflector 11 without moving parallel to the reflector 11, and the circuit board 14 may move parallel to the reflector 11 and the light source along an arrangement direction S1 by the moving member 15 to irradiate light onto the whole of the reflection surface 110 of the reflector 11. In other embodiments, the moving member 15 may be disposed on the reflecting member 11, and the light source 12, the sensing module 13 and the circuit board 14 are fixed without moving, so that the reflecting member 11 can move parallel to the sensing module 13 through the moving member 15.

The reflective element 11 of the reflective optical encoder 1 of fig. 1 is further described below.

As shown in fig. 2, in the present embodiment, the reflecting surface 110 of the reflector 11 has a rectangular shape, and the arrangement direction S1 is substantially parallel to the long side 11a of the reflecting surface 110. The reflective surface 110 has an absolute encoding region A1 and an incremental encoding region A2. Absolute encoding region A1 and incremental encoding region A2 are aligned along short side 11b of reflective surface 110. The coding pattern of absolute coding region A1 may be a 5-bit binary coding pattern, separating absolute coding region A1 into 32 barcodes. When the sensing module 13 of fig. 1 senses a specific bar code of the absolute coding region a1, it can be known where the sensing module 13 moves in parallel with respect to the reflector 11. But not limited thereto. In other embodiments, other types of absolute type encoding patterns are possible. In other embodiments, the number of barcodes of absolute coding region a1 may be other numbers, such as 24 or more.

With further reference to fig. 2 and 3, in the present embodiment, the incremental encoding area a2 of the reflection surface 110 has a plurality of sub-areas D arranged along the arrangement direction S1. Each sub-region D is rectangular in shape. The reflectances of the sub-regions D repeatedly increase and decrease in the arrangement direction S1 to form a periodic function. The incremental encoding area A2 of reflective surface 110 also has a plurality of periodic regions P. The plurality of sub-regions D within each period region P corresponds to one period of the periodic function. The length of each periodic region P in the arrangement direction S1 is any value in the range of 50 micrometers to 200 micrometers. In fig. 2 and 3, since the widths of the sub-region D, the periodic region P and the increment encoding region a2 are substantially the same in fig. 2 and 3, the sub-region D and the periodic region P are indicated by double-headed arrow line segments.

In detail, as shown in fig. 3, which shows the area III of the reflection surface 110 in fig. 2 in an enlarged manner, in the present embodiment, the reflectivity of six adjacent sub-areas D changes corresponding to one period of the periodic function, that is, the six adjacent sub-areas D form one periodic area P. The six adjacent sub-regions D include a first sub-region D1, a second sub-region D2, a third sub-region D3, a fourth sub-region D4, a fifth sub-region D5 and a sixth sub-region D6, which are sequentially arranged along the arrangement direction S1. Wherein the reflectivity of the second sub-region D2 is greater than the reflectivity of the first sub-region D1. The reflectivity of the third sub-region D3 is greater than that of the second sub-region D2. The reflectivity of the fourth sub-region D4 is substantially equal to the reflectivity of the third sub-region D3. The reflectivity of the fifth sub-region D5 is less than the reflectivity of the fourth sub-region D4. The reflectivity of the sixth sub-region D6 is less than that of the fifth sub-region D5. The reflectivity of the first sub-region D1 is substantially equal to the reflectivity of the sixth sub-region D6.

As can be seen from the above, the reflectivity of the sub-regions D repeatedly increases and decreases along the arrangement direction S1, and thus is a periodic function. A sine wave function can be fitted from the periodic function by a least squares method. The correlation coefficient between the periodic function and the sine wave function is more than 80%. The larger the correlation coefficient, the more the periodic function is approximated to a sine wave function. Wherein the correlation coefficient is calculated according to the following formula.

r represents the correlation coefficient, x represents the fitted sine wave function, y represents the periodic function, and n represents the number of points taken. If 6 points are taken in one period, n is 6.

In the present embodiment, six adjacent sub-regions D form one periodic region P, but the present invention is not limited thereto. In other embodiments, there may be other numbers of sub-regions D forming a periodic region P.

As shown in fig. 2, in the present embodiment, the change in reflectivity of all the sub-areas D of the increment encoding area a2 corresponds to 32 periods, that is, all the sub-areas D form 32 period areas P. The number of periodic regions P formed by all the subregions D of the incremental encoding region a2 and the barcode of the absolute encoding region a1 may be the same, but not limited thereto. In other embodiments, the number of periodic regions P formed by all the subregions D of the increment encoding region a2 may be other numbers, such as more than 24.

In the present embodiment, the length of the long side 11a of the reflection surface 110 is substantially equal to the length of the reflection element 11 along the arrangement direction S1, but the invention is not limited thereto. In other embodiments, the length of the long side 11a of the reflective surface 110 may be more than 90% of the long side of the reflective member 11 along the arrangement direction S1.

In the present embodiment, the lengths of the sub-regions D arranged along the arrangement direction S1 may be substantially the same as each other, but not limited thereto.

Referring to fig. 4, a sensing module of the reflective optical encoder of fig. 1 is shown. In the present embodiment, the sensing module 13 includes a plurality of photosensitive elements 131 arranged in an array along the arrangement direction S1. The photosensitive element 131 is located on the sensing surface 130. The plurality of reflectivities of the plurality of sub-regions D of the incremental encoding region a2 are sensed by the plurality of photosensitive elements 131 of the sensing module 13. Each photosensitive element 131 has the same shape and size, and may be rectangular, but not limited thereto. In other embodiments, the shape of the photosensitive assembly 131 can be other shapes.

The operation of the reflective optical encoder 1 of fig. 1 will be described below. Referring to fig. 5, it shows that the sensing device of fig. 4 senses the intensity of the light reflected by each area of the reflection surface of fig. 3. When initializing the reflective optical encoder 1, the intensity of the light reflected by the reflective surface 110 of the reflector 11 of fig. 3 is sensed by one of the photosensitive elements 131 of the sensing module 13 of fig. 4. The photosensitive element 131 scans from one end of the reflective surface 110 to the other end of the reflective surface 110 in the arrangement direction S1, and an intensity curve F1 depicted by a solid line in fig. 5 is obtained. The area of the intensity curve F1 under the line segment in each sub-region D can represent the reflectivity in this sub-region D.

In fig. 5, a sine wave function F2 is fitted from the intensity curve F1 by the least squares method. In the present embodiment, the correlation coefficient between the intensity curve F1 and the sine wave function F2 is 80% or more, which means that the intensity curve F1 is similar to the sine wave function F2. The sensing module 13 records the sine wave function F2. Then, by comparing the intensity and the reflectivity of the light sensed by the plurality of photosensitive assemblies 131 with the sinusoidal function F2 and the area under the line, the relative position and the parallel relative movement distance between the reflective element 11 and the sensing module 13 can be known.

Referring to fig. 6, a schematic cross-sectional view of the reflector of fig. 2 is shown. An example of a method of manufacturing the reflector 11 of fig. 2 is explained below. As shown in fig. 6, in the present embodiment, the reflector 11 includes a substrate 111 and a plurality of reflective films 112 respectively disposed in the plurality of sub-regions D. The reflective surface 110 is a surface of a plurality of reflective films 112. The reflective member 11 reflects light through the plurality of reflective films 112. In order to form a plurality of reflective films 112 on the substrate 111, a shield 9 may be suspended above the substrate 111. The shield 9 has a plurality of openings 90 arranged in the arrangement direction S1, each opening 90 corresponding to each period of the periodic function. Through a plating process with a slight degree of anisotropy, such as sputtering, a reflective material M for forming the reflective film 112 may be deposited on the surface of the substrate 111 through the opening 90 from above the shield 9 to form a plurality of reflective films 112, wherein the reflective material M may be a metal material, but not limited to a metal material, or may be dielectrics with different refractive indexes, such as ITO or SiO₂。

In the present embodiment, the thickness T of the plurality of reflective films 112 formed is greater than or equal to 0 nm and less than or equal to 100 nm. In this thickness range, the reflectance is increased as the thickness T of the reflective film 112 is increased. By the above manufacturing method, the thickness T of the plurality of reflective films 112 formed is continuously curved along the arrangement direction S1. The thickness T of the plurality of reflective films 112 is thicker at a position corresponding to the center line of the opening 90 and thinner at a position corresponding to the entity of the shield 9 (i.e., a position not opened). The average value of the thicknesses T of the adjacent reflective films 112 is different. The average value of the thickness T of each reflective film 112 located in each sub-region D is proportional to the reflectivity of this sub-region D. In the present embodiment, the thickness T of the plurality of reflective films 112 is formed to approximate a sine wave function. In other words, the sine wave function can be fitted from the thicknesses T of the plurality of reflective films 112 by a least squares method. The thickness T of the reflective films 112 and the coefficient of correlation of the sine wave function can reach more than 80%.

Fig. 7 is a partially enlarged schematic view of a reflector according to another embodiment of the invention. As shown in fig. 7, in the present embodiment, within the increment encoding area a2, the reflection surface 210 of the reflection member 21 is a surface of a plurality of reflection films 212. The thickness of each reflective film 212 is substantially uniform in each sub-region D. The thicknesses of the plurality of reflection films 212 located in the adjacent plurality of sub-regions D are different.

In the present embodiment, the reflectivity of six adjacent sub-regions D varies corresponding to one period of the periodic function, that is, the six adjacent sub-regions D form one periodic region P. The six adjacent sub-regions D include a first sub-region D1, a second sub-region D2, a third sub-region D3, a fourth sub-region D4, a fifth sub-region D5 and a sixth sub-region D6, which are sequentially arranged along the arrangement direction S1. Wherein the reflectivity of the second sub-region D2 is greater than the reflectivity of the first sub-region D1. The reflectivity of the third sub-region D3 is greater than that of the second sub-region D2. The reflectivity of the fourth sub-region D4 is substantially equal to the reflectivity of the third sub-region D3. The reflectivity of the fifth sub-region D5 is less than the reflectivity of the fourth sub-region D4. The reflectivity of the sixth sub-region D6 is less than that of the fifth sub-region D5. The reflectivity of the first sub-region D1 is substantially equal to the reflectivity of the sixth sub-region D6. The reflectivities of the subregions D repeatedly increase and decrease along the arrangement direction S1 to form a periodic function. The thickness of the reflective film 212 in each sub-region D is proportional to the reflectivity of the sub-region D.

The reflector 21 shown in fig. 7 may also be used in the reflective optical encoder 1 shown in fig. 1 instead of the reflector 11 shown in fig. 1.

Referring to fig. 8, a partially enlarged schematic view of a reflector according to another embodiment of the invention is shown. As shown in fig. 8, in the present embodiment, within the increment encoding area a2, the reflecting surface 310 of the reflecting member 31 is a surface of a plurality of reflecting films 312. The thickness of each reflective film 312 is substantially uniform in each sub-region D. The thicknesses of the plurality of reflection films 312 positioned at the adjacent plurality of sub-regions D are different.

In the present embodiment, the reflectivity of four adjacent sub-regions D varies corresponding to one period of the periodic function, that is, the four adjacent sub-regions D form one periodic region P. The four adjacent sub-regions D include a first sub-region D1, a second sub-region D2, a third sub-region D3 and a fourth sub-region D4, which are sequentially arranged along the arrangement direction S1. Wherein the reflectivity of the second sub-region D2 is greater than the reflectivity of the first sub-region D1. The reflectivity of the third sub-region D3 is greater than the reflectivity of the second sub-region D2. The reflectivity of the fourth sub-region D4 is less than the reflectivity of the third sub-region D3. The reflectivity of the first sub-region D1 is less than the reflectivity of the fourth sub-region D4. The reflectances of the subregions D repeatedly increase and decrease in the arrangement direction S1 to form a periodic function. The thickness of the reflective film 312 in each sub-region D is proportional to the reflectivity of the sub-region D.

The reflective member 31 shown in fig. 8 may also be used in the reflective optical encoder 1 shown in fig. 1 instead of the reflective member 11 shown in fig. 1.

Fig. 9 is a partially enlarged schematic view of a reflector according to another embodiment of the invention. As shown in fig. 9, in the present embodiment, within the increment encoding area a2, the reflection surface 410 of the reflection member 41 is a surface of the plurality of reflection films 412.

In the present embodiment, the reflection surface 410 has a plurality of periodic regions P, and a plurality of sub-regions D in each periodic region P correspond to one period of the periodic function. The reflector 41 includes a plurality of reflective films 412 in each of the periodic regions P. The plurality of reflection films 412 located in each periodic region P corresponds to one period of the periodic function. Each of the reflective films 412 has an isosceles trapezoid shape. The upper and lower bottoms of each reflective film 412 are substantially parallel to the arrangement direction S1. The plurality of reflective films 412 in each periodic region P are arrayed in another array direction S2 substantially perpendicular to the array direction S1.

In the present embodiment, the reflectivity of six adjacent sub-regions D varies corresponding to one period of the periodic function, that is, the six adjacent sub-regions D form one periodic region P. The six adjacent sub-regions D include a first sub-region D1, a second sub-region D2, a third sub-region D3, a fourth sub-region D4, a fifth sub-region D5 and a sixth sub-region D6, which are sequentially arranged along the arrangement direction S1. Wherein the area of the plurality of reflective films 412 located in the second sub-region D2 is larger than the area of the plurality of reflective films 412 located in the first sub-region D1. The area of the plurality of reflective films 412 positioned in the third sub-region D3 is larger than the area of the plurality of reflective films 412 positioned in the second sub-region D2. The area of the plurality of reflective films 412 located in the fourth sub-region D4 is substantially equal to the area of the plurality of reflective films 412 located in the third sub-region D3. The area of the plurality of reflective films 412 positioned in the fifth sub-region D5 is smaller than the area of the plurality of reflective films 412 positioned in the fourth sub-region D4. The area of the plurality of reflective films 412 located in the sixth sub-region D6 is smaller than the area of the plurality of reflective films 412 located in the fifth sub-region D5. The area of the plurality of reflective films 412 located in the first sub-region D1 is substantially equal to the area of the plurality of reflective films 412 located in the sixth sub-region D6. Moreover, the area of the reflective film 412 in each sub-region D is proportional to the reflectivity of the sub-region D.

Accordingly, the reflectivity of the second sub-region D2 is greater than that of the first sub-region D1. The reflectivity of the third sub-region D3 is greater than that of the second sub-region D2. The reflectivity of the fourth sub-region D4 is substantially equal to the reflectivity of the third sub-region D3. The reflectivity of the fifth sub-region D5 is less than the reflectivity of the fourth sub-region D4. The reflectivity of the sixth sub-region D6 is less than that of the fifth sub-region D5. The reflectivity of the first sub-region D1 is substantially equal to the reflectivity of the sixth sub-region D6. The reflectivity of the plurality of sub-regions D repeatedly increases and decreases along the arrangement direction S1 to form a periodic function.

In the present embodiment, the three reflective films 412 in each periodic region P are arranged along the arrangement direction S2, but not limited thereto. In other embodiments, there may be other numbers of reflective films 412 in each periodic region P. However, in the case of a plurality of reflection films 412, if one of the reflection films 412 of the reflection member 41 is contaminated or damaged to a small extent, the other reflection films 412 can share the influence of the contamination or damage on the reflectance of each sub-region D, as compared with the single reflection film 412. In addition, in other embodiments, the shape of each reflective film 412 may also be an isosceles triangle or other shapes.

The reflector 41 shown in fig. 9 may also be used in the reflective optical encoder 1 shown in fig. 1 instead of the reflector 11 shown in fig. 1.

Please refer to fig. 10, 11, 12 and 13. FIG. 10 is a schematic cross-sectional view of a reflective optical encoder according to another embodiment of the present invention. Fig. 11 illustrates the reflector of fig. 10. Fig. 12 is a partially enlarged schematic view of the reflecting member of fig. 11. FIG. 13 illustrates the sense module of FIG. 10. A reflective optical encoder 5 according to another embodiment of the present invention is described below.

As shown in fig. 10, in the present embodiment, the reflective optical encoder 5 includes a reflector 51, a light source 52, a sensing module 53, a circuit board 54 and a motor 56. The reflector 51 has a reflective surface 510. The light source 52 is used for emitting a light ray E1 to the reflective member 51 to illuminate the reflective surface 510 of the reflective member 51. The sensing module 53 has a sensing surface 530 facing the reflector 51. The sensing surface 530 of the sensing module 53 is used for receiving a light ray E2 reflected by the reflecting surface 510. The light source 52 and the sensing module 53 are disposed on the circuit board 54. A driving shaft 560 of the motor 56 is disposed at a center C of the reflecting member 51. The motor 56 is used for driving the reflection element 51 to rotate relative to the sensing module 53, so that the reflection element 51 and the sensing module 53 can rotate relative to each other along the arrangement direction S3, but not limited thereto. In other embodiments, the motor 56 may be disposed on the light source 52, the sensing module 53 and the circuit board 54, and the reflector 51 is fixed without rotation, so that the light source 52, the sensing module 53 and the circuit board 54 can rotate relative to the reflector 51 through the motor 56. In other embodiments, the light source 52 may be disposed around the reflector 51 and not rotate with the reflector 51 fixed, and the motor 56 may be disposed on the sensing module 53 and the circuit board 54, such that the sensing module 53 and the circuit board 54 can rotate relative to the reflector 51 via the motor 56.

The reflective member 51 of the reflective optical encoder 5 of FIG. 10 is further described below. As shown in fig. 11, in the present embodiment, the reflecting surface 510 of the reflecting member 51 has a circular shape, and the arrangement direction S3 is the circumferential direction of the reflecting surface 510. Reflective surface 510 has an absolute encoded region A1 and an incremental encoded region A2. The absolute encoding region A1 and the incremental encoding region A2 surround the center C of the reflective element 51. The absolute coding region A1 is located inside the incremental coding region A2, i.e., the incremental coding region A2 is located outside the absolute coding region A1. The encoding pattern of absolute encoding region A1 may be a 5-bit binary encoding pattern, separating absolute encoding region A1 into 32 barcodes. When the sensing module 53 of fig. 10 senses a specific barcode of the absolute code area a1, it can be known to which angle interval the sensing module 53 rotates relative to the reflective element 51. But not limited thereto. In other embodiments, other types of absolute type encoding patterns are possible. In other embodiments, the number of barcodes of absolute coding region a1 may be other numbers, such as 24 or more.

In the present embodiment, the increment encoding area a2 of the reflection surface 510 has a plurality of sub-areas θ arranged in the arrangement direction S3. Each of the sub-regions θ has an arc shape. The reflectances of the sub-regions θ repeatedly increase and decrease along the arrangement direction S3 to form a periodic function. The reflective surface 510 further has a center C and a plurality of periodic regions P. The plurality of sub-areas θ within each period region P correspond to one period of the periodic function. Each periodic region P is arc-shaped, that is, a portion of a circle centered on the center C, and has an angle of any value in the range of 0.35 to 15 degrees.

In detail, as shown in fig. 12, the area XII of the reflection surface 510 in fig. 11 is enlarged. In the present embodiment, the reflectivity of six adjacent sub-regions θ varies corresponding to one period of the periodic function, that is, the six adjacent sub-regions θ form one periodic region P. The six adjacent sub-regions θ include a first sub-region θ 1, a second sub-region θ 2, a third sub-region θ 3, a fourth sub-region θ 4, a fifth sub-region θ 5, and a sixth sub-region θ 6, which are sequentially arranged along the arrangement direction S3. The reflectivity of the second sub-area theta 2 is larger than that of the first sub-area theta 1. The reflectivity of the third sub-area theta 3 is greater than that of the second sub-area theta 2. The reflectivity of the fourth sub-area theta 4 is substantially equal to the reflectivity of the third sub-area theta 3. The reflectivity of the fifth sub-area theta 5 is less than the reflectivity of the fourth sub-area theta 4. The reflectivity of the sixth sub-area theta 6 is less than the reflectivity of the fifth sub-area theta 5. The reflectivity of the first sub-area θ 1 is substantially equal to the reflectivity of the sixth sub-area θ 6.

As can be seen from the above, the reflectivity of the sub-regions θ repeatedly increases and decreases along the arrangement direction S3, and thus is a periodic function. The periodic function can be fitted to a sine wave function by a least squares method. The correlation coefficient between the periodic function and the sine wave function is more than 80%. The larger the correlation coefficient, the more the periodic function is approximated to a sine wave function.

In the present embodiment, six adjacent sub-regions θ form one periodic region P, but the present invention is not limited to this. In other embodiments, there may be other numbers of sub-regions θ forming one period region P. In the present embodiment, the arrangement direction S3 is a clockwise direction, but not limited thereto. In other embodiments, the arrangement direction S3 may be a counterclockwise direction.

As shown in fig. 11, in the present embodiment, the change in the reflectivity of all the sub-areas θ of the increment encoding area a2 corresponds to 32 periods, that is, all the sub-areas θ form 32 period areas P. The number of periodic regions P formed by all the sub-regions θ of the increment encoding region a2 and the number of barcodes of the absolute encoding region a1 may be the same, but not limited thereto. In other embodiments, the number of the periodic regions P formed by all the sub-regions θ of the increment encoding region a2 may be other numbers, for example, more than 24.

In the present embodiment, the plurality of sub-regions θ are arranged around the center C of the reflector 51 for a full circle, but not limited thereto.

In the present embodiment, the angles of the sub-regions θ along the arrangement direction S3 may be substantially the same as each other, but not limited thereto.

In the present embodiment, the reflection surface 510 has an absolute encoding area a1 and an incremental encoding area a2, but not limited thereto. In other embodiments, the absolute coding region a1 may be omitted, and when the reflection element 51 and the sensing module 53 rotate relatively, the relative rotation angle of the reflection element 51 and the sensing module 53 can be known according to the number of the periodic regions P sensed by the sensing module 53.

Referring to fig. 13, a sensing module of fig. 10 is shown. In the present embodiment, the sensing module 53 includes a plurality of photosensitive elements 531 arranged in an array along the arrangement direction S3. The photosensitive element 531 is located on the sensing surface 530. The plurality of reflectivities of the plurality of sub-regions θ of the incremental encoding region a2 are sensed by the plurality of photosensitive elements 531 of the sensing module 53. The shape of each photosensitive element 531 may be rectangular or arc, but not limited thereto. In other embodiments, the shape of the photosensitive member 531 can be other shapes. In other embodiments, the sensing module 13 shown in FIG. 4 can also be used in the reflective optical encoder 5 shown in FIG. 10 instead of the sensing module 53 shown in FIG. 10.

In addition, when the reflector 11 shown in fig. 2 is changed to a circular shape, the reflector 51 shown in fig. 11 can be used, and the reflective optical encoder 5 shown in fig. 10 can be further used. The reflective member 21 shown in fig. 7, the reflective member 31 shown in fig. 8, and the reflective member 41 shown in fig. 9 may be changed to a circular shape in the same manner, and may be further used in the reflective optical encoder 5 shown in fig. 10 instead of the reflective member 51 shown in fig. 10.

In summary, in the reflective optical encoder according to an embodiment of the invention, the reflectivity of the sub-regions of the reflective surface of the reflective element is repeatedly increased or decreased along an arrangement direction to form a periodic function, so that when the sensing module senses the reflectivity of the sub-regions in one period of the periodic function, the situation that the reflective element and the sensing module relatively rotate or move in parallel can be known according to the reflectivity. Further, even if the size or angle of the reflecting member corresponding to one period region is narrow, the phenomenon of slit interference is not likely to occur. Therefore, the precision of the reflective optical encoder can be improved by narrowing the size or angle of the reflective member corresponding to one period.

[ description of symbols ]

1. 5 … reflective optical encoder

11. 21, 31, 41, 51 … reflector

110. 210, 310, 410, 510 … reflective surface

111 … base plate

112. 212, 312, 412 … reflective film

11a … long side

11b … short side

12. 52 … light source

13. 53 … sensing module

130. 530 … sensing surface

131. 531 … photosensitive assembly

14. 54 … circuit board

15 … moving part

56 … Motor

560 … drive shaft

9 … Shielding

90 … opening holes

The absolute coding region of A1 …

A2 … incremental coding region

Center of C …

D. Sub-regions D1, D2, D3, D4, D5 and D6 …

E1, E2 … ray

F1 … intensity Curve

F2 … sine wave function

M … reflective material

P … periodic region

The arrangement directions of S1, S2 and S3 …

T … thickness

III, XII … region

Sub-regions of theta, theta 1, theta 2, theta 3, theta 4, theta 5 and theta 6 …

Claims

1. A reflective optical encoder, comprising:

the reflecting piece is provided with a reflecting surface, the reflecting surface is provided with a plurality of sub-areas which are arranged along an arrangement direction, and a plurality of reflectivities of the sub-areas are repeatedly increased and decreased along the arrangement direction to form a periodic function;

the light source is used for emitting a light ray to irradiate the reflecting surface of the reflecting piece; and

the reflecting piece and the sensing module can rotate relative to each other or move in parallel along the arrangement direction, and the sensing module is used for receiving the light rays reflected by the reflecting surface.

2. The reflective optical encoder according to claim 1, wherein the periodic function has a correlation coefficient with a sine wave function of 80% or more.

3. The reflective optical encoder according to claim 1, wherein the reflective surface of the reflector is circular, each of the sub-regions is arc-shaped, and the arrangement direction is a circumferential direction of the reflective surface.

4. The reflective optical encoder according to claim 3, wherein the reflective surface further has a center and a plurality of periodic regions, the plurality of sub-regions in each periodic region correspond to a period of the periodic function, and each periodic region has an arc shape centered on the center and has an angle in a range from 0.35 degrees to 15 degrees.

5. The reflective optical encoder according to claim 3, further comprising a motor having a driving shaft disposed at a center of the reflector, the motor being configured to drive the reflector to rotate relative to the sensor module.

6. The reflective optical encoder of claim 3, wherein the plurality of sub-regions are arranged in a full circle around a center of the reflective surface.

7. The reflective optical encoder according to claim 1, wherein the reflective surface of the reflector is rectangular, each of the sub-regions is rectangular, and the arrangement direction is substantially parallel to the long side of the reflective surface.

8. The reflective optical encoder of claim 7, wherein the reflective surface further has a plurality of periodic regions, the plurality of sub-regions within each of the periodic regions corresponding to a period of the periodic function, each of the periodic regions having a length in the arrangement direction of any one of values in a range of 50 microns to 200 microns.

9. The reflective optical encoder according to claim 7, wherein the length of the long side of the reflective surface is 90% or more of the length of the reflective member in the arrangement direction.

10. The reflective optical encoder according to claim 1, wherein the number of periods of the plurality of reflectivities of the plurality of subregions corresponding to the periodic function is greater than 24.

11. The reflective optical encoder of claim 1, further comprising a circuit board, wherein the light source and the sensing module are disposed on the circuit board, and the circuit board can rotate or move parallel to the reflector.

12. The reflective optical encoder of claim 1, wherein the reflectivity of six adjacent sub-regions varies with a period of the periodic function, the six adjacent sub-regions include a first sub-region, a second sub-region, a third sub-region, a fourth sub-region, a fifth sub-region and a sixth sub-region arranged in sequence along the arrangement direction, the reflectivity of the second sub-region is greater than the reflectivity of the first sub-region, the reflectivity of the third sub-region is greater than the reflectivity of the second sub-region, the reflectivity of the fourth sub-region is substantially equal to the reflectivity of the third sub-region, the reflectivity of the fifth sub-region is less than the reflectivity of the fourth sub-region, the reflectivity of the sixth sub-region is less than the reflectivity of the fifth sub-region, and the reflectivity of the first sub-region is substantially equal to the reflectivity of the sixth sub-region.

13. The reflective optical encoder according to claim 1, wherein the reflectivity of four adjacent sub-regions varies with a period of the periodic function, the reflectivity of the second sub-region is greater than the reflectivity of the first sub-region, the reflectivity of the third sub-region is greater than the reflectivity of the second sub-region, the reflectivity of the fourth sub-region is less than the reflectivity of the third sub-region, and the reflectivity of the first sub-region is less than the reflectivity of the fourth sub-region.

14. The reflective optical encoder according to claim 1, wherein the reflector comprises a substrate stacked on each other and a plurality of reflective films respectively disposed in the sub-regions, the reflective surface is disposed on the reflective film, and a thickness of each reflective film is greater than 0 nm and less than or equal to 100 nm.

15. The reflective optical encoder according to claim 14, wherein the thicknesses of the reflective films in adjacent sub-regions are different, and the thickness of each reflective film in each sub-region is proportional to the reflectivity of each sub-region.

16. The reflective optical encoder according to claim 14, wherein the thicknesses of the reflective films in the sub-regions are continuously curved along the arrangement direction, the average value of the thicknesses of the adjacent reflective films is different, and the average value of the thicknesses of the reflective films in the sub-regions is proportional to the reflectivity of the sub-regions.

17. The reflective optical encoder of claim 1, wherein the reflective surface further has a plurality of periodic regions, the plurality of sub-regions in each of the periodic regions corresponds to a period of the periodic function, the reflector includes a plurality of reflective films in each of the periodic regions, the reflective surface is disposed on the plurality of reflective films, the plurality of reflective films in each of the periodic regions corresponds to a period of the periodic function, each of the reflective films has an isosceles trapezoid shape with upper and lower bases substantially parallel to the arrangement direction, and the plurality of reflective films in each of the periodic regions are arrayed in another arrangement direction substantially perpendicular to the arrangement direction.

18. The reflective optical encoder according to claim 17, wherein the area of the reflective films in each of the sub-regions is proportional to the reflectivity of each of the sub-regions.

19. The reflective optical encoder according to claim 1, wherein the sensor module comprises a plurality of photosensitive elements arranged in an array along the arrangement direction.