Coded-disc-free optical encoder

Abstract

The utility model provides an optical encoder without a code disc. The optical encoder comprises a shaft body and an optical flow sensor. The shaft body is used for being connected with a target object and is configured to rotate around the axis of the shaft body under driving of the target object. Wherein the shaft body is provided with at least two surface image areas, the at least two surface image areas have different surface features, and the at least two surface image areas are adjacently arranged in the circumferential direction of the shaft body; the optical flow sensor is arranged on one side of the radial direction of the shaft body in an offset mode and used for obtaining an optical flow image of the shaft body and obtaining the rotation displacement of the shaft body according to the optical flow image. The optical flow sensor also determines the zero position of the coded-disc-free optical encoder according to the jump of the image features of the joint part of the at least two surface image areas in the optical flow image; the optical flow sensor is configured to determine the current angle of the shaft body based on the ratio of the accumulated displacement of the shaft body from the zero position to the current position to the calibrated displacement of each circle.

Description

TECHNICAL FIELD

[0001] The utility model relates to encoder technical field, especially a kind of codeless optical encoder. BACKGROUND

[0002] The existing rotary encoder includes mechanical encoder, optical encoder, magnetic encoder, electromagnetic induction encoder, capacitive encoder and the like. Among them, optical encoder and magnetic encoder are more widely used.

[0003] Optical encoder generally includes light emitting element, photosensitive element and code disk. The accuracy of optical encoder depends on the grating accuracy of code disk, and the material and machining accuracy of code disk are required to be higher. The processing circuit of optical absolute encoder is also relatively complex. This leads to higher processing cost and larger size of optical encoder.

[0004] Magnetic encoder is composed of permanent magnet and hall element. Magnetic encoder uses magnetic field change to detect angle, and is less affected by dust pollution. However, the accuracy of magnetic encoder is not as good as that of optical encoder, and magnetic encoder cannot be applied in the scene where external magnetic field changes. SUMMARY

[0005] The utility model aims at providing a kind of codeless optical encoder to solve the problems of complex structure or insufficient accuracy of the existing rotary encoder.

[0006] To solve the above technical problems, the utility model provides a kind of codeless optical encoder, which comprises: shaft body and optical flow sensor;

[0007] The shaft body is used to be connected with the target object and is configured to rotate around its axis under the driving of the target object. The shaft body has at least two surface image areas, and the at least two surface image areas have different surface characteristics and are arranged adjacently along the circumferential direction of the shaft body.

[0008] The optical flow sensor is biased on one side of the radial direction of the shaft body, used to obtain the optical flow image of the shaft body, and to obtain the displacement of the shaft body rotation according to the optical flow image. The optical flow sensor also determines the zero position of the codeless optical encoder according to the jump of image characteristics of the junction of the at least two surface image areas in the optical flow image.

[0009] The optical flow sensor is configured to determine the current angle of the shaft body based on the ratio of the cumulative displacement of the shaft body from the zero position to the current position to the calibrated displacement per week.

[0010] Optionally, the junction of the at least two surface image areas extends linearly along the axial direction of the shaft body.

[0011] Optionally, the surface feature includes a reflection coefficient or a color.

[0012] Optionally, the optical flow sensor includes a light source, an image acquisition unit, and a processing unit.

[0013] The light source is configured to irradiate the shaft body.

[0014] The image acquisition unit is configured to acquire an optical flow image of the shaft body.

[0015] The processing unit is configured to calculate the displacement, the zero position, and a current angle of the shaft body.

[0016] Optionally, the encoder further includes a filter disposed between the light source and the image acquisition unit, configured to filter out light of a wavelength not matching that of the light source.

[0017] Optionally, the optical flow sensor is further configured to, in a calibration mode, acquire a total displacement of the shaft body after a plurality of rotations, divide the total displacement into a plurality of partial displacements according to the zero position, and calibrate a mean value of the plurality of partial displacements as the per-rotation displacement.

[0018] Optionally, the shaft body has two surface image areas, and a circumferential proportion of the two surface image areas on the shaft body is 50%±0.5%.

[0019] Optionally, the optical flow sensor determines a 0° position and a 180° position of the encoder according to a jump of surface image features of two junctions of the two surface image areas in the optical flow image.

[0020] The optical flow sensor is configured to determine a current angle of the shaft body with the 0° position and the 180° position as zero positions of the encoder.

[0021] Optionally, the optical flow sensor is configured to determine an angular velocity of the shaft body based on a current displacement of the shaft body, the calibrated per-rotation displacement, and a sampling interval of the optical flow image.

[0022] Optionally, the optical flow sensor is configured to determine a direction of rotation of the shaft body based on a positive or negative of the current displacement of the shaft body.

[0023] In summary, the codeless disc optical encoder provided by the utility model comprises: a shaft body and an optical flow sensor; the shaft body is used for being connected with a target object and is configured to rotate around its own axis under the driving of the target object; wherein the shaft body has at least two surface image areas, the at least two surface image areas have different surface features, and the at least two surface image areas are adjacently arranged along the circumference of the shaft body; the optical flow sensor is offset to one side of the shaft body in the radial direction, is used for acquiring the optical flow image of the shaft body, and obtains the displacement amount of the rotation of the shaft body according to the optical flow image; the optical flow sensor further determines the zero position of the codeless disc optical encoder according to the jump of the image features of the joint part of the at least two surface image areas in the optical flow image; the optical flow sensor is configured to determine the current angle of the shaft body based on the ratio of the accumulated displacement amount of the shaft body from the zero position to the current position to the calibrated displacement amount per week.

[0024] In this way, the zero position can be determined by identifying the jump of the surface image features of the joint part of the surface image areas on the shaft body. Furthermore, the current accurate angle of the shaft body can be obtained by incrementally accumulating and calculating the displacement amount based on the zero position, and the precision is high. Since the code disc structure of the existing optical encoder does not need to be arranged, the structure is simple and the cost is low. Meanwhile, since the detection is realized based on the optical method of the optical flow sensor, the detection can be applied to the scene where the external magnetic field changes. BRIEF DESCRIPTION OF DRAWINGS

[0025] Those skilled in the art will understand that the provided drawings are for the purpose of better illustrating the utility model and do not constitute any limitation on the scope of the utility model. Among them:

[0026] Figure 1 is a schematic view of the shaft body of the utility model embodiment.

[0027] Figure 2 is a schematic view of the codeless disc optical encoder of the utility model embodiment.

[0028] Figure 3 is a schematic view of the change of the average brightness of pixels of the utility model embodiment.

[0029] Figure 4 is a schematic view of the change of the displacement amount of the utility model embodiment.

[0030] In the drawings:

[0031] 1-shaft body; 10-joint part; 11-body surface; 12-black and gray surface; 2-optical flow sensor; 21-light source; 22-image acquisition unit; 23-processing unit; 24-filter. DETAILED DESCRIPTION

[0032] To make the purposes, advantages and characteristics of the present application more clear, the present application will be further described in detail below in combination with the drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clearly assist in describing the purposes of the embodiments of the present application. In addition, the structures shown in the drawings are often part of the actual structures. In particular, the emphasis of each drawing needs to be different, and sometimes different scales are used.

[0033] As used in the present application, the singular forms "a", "an", and "the" include plural referents, the term "or" is generally used in the sense of "and / or", the term "at least one" is generally used in the sense of "one or more", the term "at least two" is generally used in the sense of "two or more", and in addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first", "second", "third" can explicitly or implicitly include one or at least two features, "one end" and "the other end" and "proximal end" and "distal end" generally refer to two parts corresponding to each other, which not only includes the end point. In addition, as used in the present application, "mounting", "connection", "connection", one element "provided" in another element should be understood broadly, and generally only indicates that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the two elements can be directly or indirectly connected, coupled, cooperated or transmitted through intermediate elements, and cannot be understood as indicating or implying the spatial position relationship between the two elements, i.e. one element can be in the interior, exterior, upper, lower or one side of another element, etc. Any orientation, unless the content is otherwise explicitly indicated. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, directional terms such as upper, lower, up, down, left, right, etc. are used with respect to the exemplary embodiments as they are shown in the drawings, upward or upward direction is toward the top of the corresponding drawing, and downward or downward direction is toward the bottom of the corresponding drawing.

[0034] The present application aims to provide a kind of codeless optical encoder, to solve the problem of complex structure or insufficient precision of existing rotary encoder. The following description is made with reference to the drawings.

[0035] The inventor has found that, for an incremental encoder, determining a reliable and accurate zero point helps to improve the output accuracy. Especially for a rotary encoder, the position can be reset to zero every time the zero point is passed, so that the displacement amount of each rotation can be accurately counted based on the zero point. In a conventional optical encoder with a code disk, the zero point can be defined by setting a specific structure on the code disk. However, for the code diskless optical encoder of the present embodiment, the structure of the code disk is missing, so it is difficult to accurately define the zero point.

[0036] Based on the above research, reference is made to Figure 1 and Figure 2 The present embodiment provides a code diskless optical encoder, which comprises: a shaft body 1 and an optical flow sensor 2; the shaft body 1 is configured to be connected to a target object and to rotate around its own axis under the driving of the target object; wherein the shaft body 1 has at least two surface image areas, the at least two surface image areas have different surface features, and the at least two surface image areas are arranged adjacent to each other along the circumference of the shaft body 1; the optical flow sensor 2 is offset to one side of the shaft body 1 in the radial direction, configured to obtain an optical flow image of the shaft body 1, and to obtain the displacement amount of the shaft body 1 based on the optical flow image; the optical flow sensor 2 further determines the zero position of the code diskless optical encoder based on the jump of the image features of the junction part 10 of the at least two surface image areas in the optical flow image; the optical flow sensor 2 is configured to determine the current angle of the shaft body 1 based on the ratio of the cumulative displacement amount of the shaft body 1 from the zero position to the current position to the calibrated displacement amount per week.

[0037] The code diskless optical encoder provided by the present embodiment sets at least two surface image areas with different surface features on the shaft body 1, so that the optical flow image obtained by the optical flow sensor 2 can reflect the jump of the image features of the junction part 10 of the surface image areas, and the zero position of the code diskless optical encoder is determined based on the jump, and then the incremental operation is performed based on the zero position, so that the accurate angle of the shaft body 1 can be obtained, and the precision is high. Since the code disk structure of the existing optical encoder does not need to be set, the structure is simple and the cost is low. At the same time, since the detection is realized based on the optical flow sensor, it can be applied to scenes with external magnetic field changes.

[0038] In one embodiment, the optical flow sensor 2 is in a fixed or stationary state relative to the shaft body 1, and can take pictures of the shaft body 1 at a certain period, so as to obtain a series of optical flow images of the shaft body 1. When the shaft body 1 rotates around the shaft under the driving of the target object, it can be understood that the optical flow image obtained by the optical flow sensor 2 will also change. Based on the optical flow image, the displacement amount of the shaft body 1 can be obtained.

[0039] Further, since the at least two surface image areas have different surface characteristics, when the interface 10 between the at least two surface image areas rotates past the optical flow sensor 2, the image characteristics of the optical flow image captured by the optical flow sensor 2 will change. The image characteristics can be, for example, at least one of the average pixel brightness frame_avg of the image, the standard deviation of the image, the sum of the absolute values of the pixel differences (SAD) of the image, and the correlation coefficient (CORR) of the image. The surface characteristics include, for example, the reflection coefficient or color.

[0040] In Figure 1 In the example shown, the shaft body 1 includes two surface image areas in the circumferential direction, which have two different reflection coefficients respectively. One of the surface image areas is the body surface 11 of the shaft body 1 material, for example, the original color or polished bright surface of the metal, and the other surface image area is the black gray surface 12 after surface treatment. Based on the different reflection coefficients, the image characteristics can be, for example, the average pixel brightness frame_avg of the image. In other embodiments, the different surface image areas can also be distinguished by the same or similar reflection coefficients but different colors. At this time, the image characteristics can also be, for example, the average pixel hue of the image.

[0041] Preferably, the interface 10 between the at least two surface image areas extends linearly in the axial direction of the shaft body 1. The linear extension of the interface 10 in the axial direction facilitates the rapid change of the image characteristics, so that the zero position can be clearly located.

[0042] Please refer to Figure 3 , which shows that the shaft body 1 rotates one revolution. Figure 1 The change of the average pixel brightness frame_avg of the optical flow image captured by the optical flow sensor 2 is shown in the example of the shaft body 1 rotating one revolution. As can be seen, in the optical flow image corresponding to the shaft body 1 rotating one revolution, the average pixel brightness frame_avg has two jumps, which can be understood as corresponding to the two interfaces 10 between the two surface image areas of the shaft body 1. In application, any one of the jump edges can be selected as the zero position of the codeless optical encoder. As can be understood, when the shaft body 1 includes a larger number of surface image areas, a larger number of jumps will occur, and any one of the jump edges can also be selected as the zero position of the codeless optical encoder. Since the size of the surface image area is not set, the distance between the two jump edges is not known, but the selected jump edge will repeat every revolution of the shaft body 1, so the period of one revolution of the shaft body 1 can be determined according to the selected jump edge.

[0043] With the rotation of the shaft body 1, the displacement amount dx of the shaft body 1 can be calculated according to the optical flow image captured by the optical flow sensor 2. The displacement amount dx can be calculated based on the current optical flow image and the optical flow image sequence calibrated when the shaft body 1 rotates one round. For details, please refer to the description of the calibration mode below. Further, based on the zero position setting, the optical flow sensor 2 can accumulate the displacement amount of the shaft body 1 from the zero position to the current position to obtain the accumulated displacement amount dx_sum. According to the ratio of the accumulated displacement amount dx_sum and the per-round displacement amount dx_sum_avg calibrated when the shaft body 1 rotates one round, the angle angle that the shaft body 1 rotates from the zero position can be determined, i.e., angle = dx_sum / dx_sum_avg*360.

[0044] Although in some embodiments, the number, proportion, size, etc. of the surface image regions are not limited, and only one of the interface positions 10 of different surface image regions is used for zeroing, in some preferred embodiments, the surface image regions can be set to each occupy half of the circumference of the shaft body 1, i.e., the shaft body 1 has two surface image regions, and the circumferential proportion of the two surface image regions on the shaft body 1 is 50%±0.5%. Further, the circumferential proportion of the two surface image regions is 50%±0.1%.

[0045] When the two surface image regions are set to each occupy half of the circumference of the shaft body 1, the optical flow sensor 2 determines the 0° position and the 180° position of the codeless optical encoder according to the jump of the surface image features of the two interface positions 10 of the two surface image regions in the optical flow image. The optical flow sensor 2 is configured to determine the current angle of the shaft body 1 by taking the 0° position and the 180° position as the zero positions of the codeless optical encoder, respectively.

[0046] The inventors further found that since the codeless optical encoder of the present embodiment does not have a code disc, the main source of the angle calculation error is the calculation error of the displacement amount dx. Without limiting the proportion of the surface image regions, only one of the interface positions 10 can be used as the zero position, and the shaft body 1 returns to zero once every 360°. In some embodiments, the error of the accumulated displacement amount dx_sum can be controlled within 0.5%. By setting the proportion of the surface image regions, when the two surface image regions are set to each occupy half of the circumference of the shaft body 1, both of the two interface positions 10 of the two surface image regions can be used as the zero positions for the accumulated displacement amount dx_sum to return to zero, which is equivalent to that the shaft body 1 returns to zero once every 180°, effectively reducing the error of the accumulated displacement amount dx_sum and improving the accuracy. It can be understood that when the 0° position and the 180° position are taken as the zero positions of the codeless optical encoder, the per-round displacement amount dx_sum_avg can be divided by 2 when applied.

[0047] Since the codeless optical encoder of the present embodiment does not have physical structure such as code disk, it is necessary to configure into calibration mode to calibrate and define some basic parameters before first use after installation of the codeless optical encoder is completed, or after significant structural changes.

[0048] In the calibration mode, the shaft body 1 can be driven to rotate at a fixed speed for a plurality of rounds, for example, 200 rounds. In this process, the optical flow sensor 2 takes pictures at a set sampling interval t to obtain a series of optical flow images and obtain image features of these optical flow images, such as pixel average brightness frame_avg. The relationship between the pixel average brightness frame_avg and the time is shown in Figure 3 Select one of the jump edges as the zero position, for example, define the jump edge from high to low as the zero position, and divide the 200 rounds of optical flow images into 200 groups of per-round optical flow image data based on the zero position.

[0049] It can be understood that one round of rotation of the shaft body 1 corresponding to each group of per-round optical flow image data, since the sampling interval t is known and the shaft body 1 is configured to rotate at a fixed speed, the number of optical flow images contained in each group of per-round optical flow image data is also known and determined, based on which the displacement dx of the shaft body 1 rotated corresponding to each two adjacent optical flow images can be calculated. Thereafter, in subsequent use, by comparing a plurality of optical flow images taken by the optical flow sensor 2 with the per-round optical flow image data, the displacement dx of the shaft body 1 rotated when the plurality of optical flow images are taken can be known.

[0050] Returning to the calibration mode for further description, the optical flow sensor 2 is further configured to, in the calibration mode, obtain a total displacement of the shaft body 1 rotating for a plurality of rounds, divide the total displacement into a plurality of partial displacements according to the zero position, and calibrate the average of the plurality of partial displacements as the per-round displacement. Continue to take the above example as an example, with the rotation of the shaft body 1, the displacement dx is accumulated, and the relationship between the accumulation of the displacement dx and the time is shown in Figure 4 Select the jump edge corresponding to Figure 3 as the zero position, and divide the total displacement of 200 rounds into 200 groups of partial displacements, and calibrate the average of the 200 groups of partial displacements as the per-round displacement dx_sum_avg.

[0051] After the calibration is completed, the non-cod disc optical encoder can enter the normal use mode. Before each use, the target and the shaft body 1 can be rotated clockwise first, and the 0° position can be found according to the jump of the selected zero position, for example, the jump of the average pixel brightness frame_avg from high to low in the calibration mode, and the current accumulated displacement dx_sum is set to 0. Then, according to the work requirement, the target and the shaft body 1 can be rotated freely, and the displacement dx of the shaft body 1 can be calculated according to the difference between the front and rear two frames of the optical flow image sequence, and the accumulated displacement dx_sum is accumulated to obtain the accumulated displacement dx_sum. Based on this, the non-cod disc optical encoder can obtain the current angle of the shaft body 1, angle = dx_sum / dx_sum_avg*360.

[0052] Further, the optical flow sensor 2 is configured to determine the angular velocity a of the rotation of the shaft body 1 based on the current displacement dx of the shaft body 1, the calibrated per-cycle displacement dx_sum_avg and the sampling interval t of the optical flow image. It can be understood that the angular velocity a = dx / dx_sum_avg*360 / t.

[0053] Further, the optical flow sensor 2 is configured to determine the direction of the rotation of the shaft body 1 based on the positive and negative of the current displacement dx of the shaft body 1. According to the direction of the rotation of the shaft body 1 in the calibration mode and the positive and negative of the displacement defined based on the direction of the rotation, the direction of the rotation of the shaft body 1 in use can be determined. For example, if the clockwise direction displacement dx is defined as positive in the calibration mode, if the actual displacement dx is positive in use, it indicates that the shaft body 1 rotates clockwise, and if the actual displacement dx is negative, it indicates that the shaft body 1 rotates counterclockwise.

[0054] Please continue to refer to Figure 2 In one embodiment, the optical flow sensor 2 includes a light source 21, an image acquisition unit 22 and a processing unit 23; the light source 21 is used to irradiate the shaft body 1; the image acquisition unit 22 is used to acquire the optical flow image of the shaft body 1; and the processing unit 23 is used to calculate the displacement, the zero position and the current angle of the shaft body 1.

[0055] The image acquisition unit 22, for example, includes an image sensor, and the light source 21 is used to irradiate the shaft body 1, so as to facilitate the image sensor to take an image. The installation position of the light source 21 is not limited, and it can be located on the same side of the shaft body 1 as the image sensor. It can be understood that the wavelength of the light emitted by the light source 21 is not limited, and it can be visible light or infrared light, etc. The image sensor of the image acquisition unit 22 is preferably adapted to the wavelength of the light emitted by the light source 21, for example, when the light source 21 emits infrared light, the image sensor is preferably an infrared image sensor. The image sensor can be selected to be multiple, and is preferably arranged in a column or an array.

[0056] Further, the codeless optical encoder further comprises a filter 24 arranged between the light source 21 and the image acquisition unit 22, for filtering out light not matching the wavelength of the light source 21. The filter 24 can only pass light of a specific wavelength, which can reduce the influence of ambient light. In some embodiments, the codeless optical encoder further preferably comprises a lens or lens group for improving imaging effect. The processing unit 23 is, for example, a programmable logic controller (PLC) or a single-chip microcomputer commonly used in the art, and those skilled in the art can understand and configure the structure and principle of the light source 21, the image acquisition unit 22, the processing unit 23, the filter 24, and the lens or lens group according to the prior art, which will not be described in detail.

[0057] In summary, the codeless optical encoder provided by the present application comprises: a shaft body and an optical flow sensor; the shaft body is used to be connected with a target object and is configured to rotate around its own axis under the driving of the target object; wherein the shaft body has at least two surface image areas, the at least two surface image areas have different surface features, and the at least two surface image areas are arranged adjacent along the circumference of the shaft body; the optical flow sensor is offset to one side of the shaft body in the radial direction, used to acquire an optical flow image of the shaft body, and to obtain a displacement amount of the rotation of the shaft body according to the optical flow image; the optical flow sensor further determines the zero position of the codeless optical encoder according to the jump of the image features of the joint part of the at least two surface image areas in the optical flow image; and the optical flow sensor is configured to determine the current angle of the shaft body based on the ratio of the cumulative displacement amount of the shaft body from the zero position to the current position to the calibrated displacement amount per week. In this way, by identifying the jump of the surface image features of the joint part of the surface image areas on the shaft body, the zero position can be determined. Further, based on the zero position, the incremental accumulation and calculation of the displacement amount can be performed, and the current accurate angle of the shaft body can be obtained, with high precision. Since the code disk structure of the existing optical encoder does not need to be set, the structure is simple and the cost is low. At the same time, since the detection is realized based on the optical flow sensor shooting, it can be applied to scenes with external magnetic field changes.

[0058] It should be noted that the above several embodiments can be combined with each other. The above description is only a description of the preferred embodiments of the present application, and does not limit the scope of the present application in any way. Any modification or modification made by a person skilled in the art based on the above disclosure is within the protection scope of the present application.

Claims

1. A code disc optical encoder characterized by, The application relates to a non-codewheel optical encoder. The shaft body is used for connecting with a target object and is configured to rotate around its own axis under the driving of the target object; wherein the shaft body has at least two surface image areas, the at least two surface image areas have different surface features, and the at least two surface image areas are arranged in adjacency along the circumferential direction of the shaft body; the optical flow sensor is offset to one side of the shaft body in the radial direction, is used for acquiring an optical flow image of the shaft body, and obtains a displacement amount of the shaft body rotation according to the optical flow image; the optical flow sensor further determines a zero position of the non-codewheel optical encoder according to the jump of the image features of the joint positions of the at least two surface image areas in the optical flow image; The optical flow sensor is configured to determine the current angle of the shaft body based on the ratio of the accumulated displacement amount of the shaft body from the zero position to the current position to the calibrated per-week displacement amount. The joint positions of the at least two surface image areas extend linearly along the axial direction of the shaft body.

2. The code disc optical encoder of claim 1, wherein, The surface features include reflection coefficients or colors.

3. The code disc optical encoder of claim 1, wherein, The optical flow sensor includes a light source, an image acquisition unit, and a processing unit; 4. The code disc optical encoder of claim 1, wherein, The light source is used for irradiating the shaft body; The image acquisition unit is used for acquiring the optical flow image of the shaft body; The processing unit is used for calculating the displacement amount, the zero position, and the current angle of the shaft body. The non-codewheel optical encoder further includes a filter, which is arranged between the light source and the image acquisition unit and is used for filtering out light with wavelengths that are not suitable for the light source.

5. The code disc optical encoder of claim 4, wherein, The optical flow sensor is further configured to, in a calibration mode, acquire a total displacement amount of the shaft body rotation for multiple weeks, divide the total displacement amount into multiple partial displacement amounts according to the zero position, and calibrate the average of the multiple partial displacement amounts as the per-week displacement amount.

6. The code disc optical encoder of claim 1, wherein, The shaft body has two surface image areas, and the circumferential proportion of the two surface image areas on the shaft body is 50%+ / -0.5%.

7. The code disc optical encoder of claim 1, wherein, The optical flow sensor determines the 0° position and the 180° position of the non-codewheel optical encoder respectively according to the jump of the surface image features of the two joint positions of the two surface image areas in the optical flow image; 8. The code disc optical encoder of claim 7, wherein, The optical flow sensor is configured to determine the current angle of the shaft body respectively with the 0° position and the 180° position as the zero position of the non-codewheel optical encoder. The optical flow sensor is configured to determine the angular velocity of the shaft body rotation based on the current displacement amount of the shaft body, the calibrated per-week displacement amount, and the sampling interval of the optical flow image.

9. The code disc optical encoder of claim 1, wherein, The optical flow sensor is configured to determine the direction of the shaft body rotation based on the positive or negative of the current displacement amount of the shaft body.

10. The code disc optical encoder of claim 1, wherein, ​

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