Photoelectric encoder and motor
By using lasers and dense stripe structures in photoelectric encoders, combined with multiple sub-array detection modules and pixel blocks, the problem of insufficient stripe spacing in existing technologies is solved, achieving higher position measurement accuracy and resolution, and improving light energy utilization and system reliability.
Patent Information
- Application Number
- CN202520480592.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2035-03-18
AI Technical Summary
Existing photoelectric encoders use incoherent light sources, which makes it difficult to achieve a stripe spacing of less than 10µm, affecting the encoder's position accuracy and resolution. Furthermore, the large divergence angle of the LED light source results in low light energy utilization.
A laser is used instead of an LED light source. By utilizing a dense stripe spacing and a high-quality laser light source, the position of the scale is measured by detecting changes in the position of the diffraction stripes. Multiple subarray detection modules and pixel blocks are used to improve signal accuracy and reliability.
It achieves higher position measurement accuracy and resolution, simplifies system design, and improves light energy utilization, system sensitivity, and reliability.
Smart Images
Figure CN223870094U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of sensors, in particular to an optical encoder and a motor. BACKGROUND
[0002] The commonly used optical encoder is generally an image encoder. An absolute code track is formed on a code disc, and a stripe structure with non-repeated pattern features is continuously formed on the absolute code track. The image on the code disc is projected onto a code reader in proportion through the irradiation of a non-coherent light source such as an LED, so that the absolute position can be located at any position in the circle. Since the stripe spacing of the code track is too small, diffraction effect will be caused. In the prior art, the amplitude and phase of the light waves emitted in all directions by the non-coherent light source such as the LED cannot be predicted, so that the pattern after diffraction cannot be effectively detected. In addition, the divergence angle of the LED light source is relatively large, basically more than 45°, which causes a large amount of light to be useless. Therefore, the LED light source needs a certain area to generate sufficient optical power, otherwise the signal amplitude received by the detector is not enough. Based on the above reasons, the stripe spacing density of the absolute code track in the prior art is difficult to reach below 10 um, which causes the position accuracy and resolution of the encoder to be unable to be improved. CONTENT OF THE UTILITY MODEL
[0003] The purpose of the present application is to provide an optical encoder and a motor, which can greatly reduce the stripe spacing, measure the position of the scale by detecting the position change of the diffraction stripes generated by the diffraction of light, and greatly improve the detection accuracy of the optical encoder.
[0004] The embodiments of the present application are implemented as follows:
[0005] In a first aspect, the embodiments of the present application provide an optical encoder, which comprises a scale, a laser and a detector. The scale is provided with a code track, and the code track comprises a plurality of stripes distributed at intervals along the extension path of the scale. When the scale moves, the laser emits light towards the code track, the light beam is diffracted towards the detector after passing through the stripes, the detector receives the diffracted light, and the position information of the scale can be obtained according to the position of the diffraction stripes.
[0006] As an optional implementation manner, the detector comprises a plurality of sub-array detection modules, the sub-array detection modules have a plurality of pixel blocks for receiving optical signals, and the plurality of pixel blocks are arranged along the movement direction of the stripes. The code track is divided into a plurality of stripe bands, the plurality of sub-array detection modules correspond to the plurality of stripe bands one by one, and each sub-array detection module detects one of the stripe bands.
[0007] As an optional implementation, the stripes include reflective stripes; the laser and the detector are arranged on the same side of the scale, and the laser emits light which is reflected and diffracted at the reflective stripes and then enters the detector.
[0008] As an optional implementation, the stripes include transmissive stripes; the laser and the detector are arranged on the two sides of the scale respectively, and the laser emits light which transmits through the transmissive stripes and then enters the detector.
[0009] As an optional implementation, at least two pixel blocks are arranged in the pitch of the diffracted stripes, for detecting the movement direction of the code track.
[0010] As an optional implementation, the pitch of the diffracted stripes is 1.6-2.5 times the distance between adjacent stripes on the code track.
[0011] As an optional implementation, the distance from the laser to the code track is denoted as L1, and the distance from the detector to the code track is denoted as L2; wherein, the value range of (L1+L2) / L1 is 1.5-10.
[0012] As an optional implementation, the distance between adjacent stripes on the code track is less than 20 times the wavelength of the light.
[0013] As an optional implementation, the laser includes an edge-emitting laser.
[0014] In a second aspect, the embodiments of the present application provide an electric machine, including an electric machine body and the photoelectric encoder described above; the photoelectric encoder is installed in the electric machine body and used for detecting the rotation position of the electric machine.
[0015] The beneficial effects of the embodiments of the present application include:
[0016] In a first aspect, the embodiments of the present application provide a photoelectric encoder, including a scale, a laser and a detector; the scale is provided with a code track, and the code track includes a plurality of stripes which are distributed along the extension path of the scale at intervals; when the scale moves, the laser emits light towards the code track, the light beam is diffracted and emitted towards the detector by the stripes, the detector receives the diffracted light, and the position information of the scale can be obtained according to the position of the diffracted stripes. Compared with the prior art, the embodiments of the present application measure the position of the scale by using dense stripe distance and high-quality laser light source and detecting the position change of the diffracted stripes, so that the encoder can realize finer position division within a circle, and the position measurement precision is improved.
[0017] In a second aspect, the embodiment of the present application provides a motor, comprising a motor body and the photoelectric encoder described above; the photoelectric encoder is installed in the motor body and used for detecting the rotating position of the motor. The motor provided by the embodiment of the present application can realize accurate control of the rotating angle by using the photoelectric encoder described above, and is beneficial to improving the control accuracy of the motor. BRIEF DESCRIPTION OF DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.
[0019] Figure 1 FIG. 1 is a structural schematic diagram of a photoelectric encoder according to an embodiment of the present application;
[0020] Figure 2 FIG. 2 is another structural schematic diagram of a photoelectric encoder according to an embodiment of the present application;
[0021] Figure 3 FIG. 3 is a third structural schematic diagram of a photoelectric encoder according to an embodiment of the present application;
[0022] Figure 4 FIG. 4 is a whole distribution diagram of a diffraction pattern obtained by simulation according to an embodiment of the present application;
[0023] Figure 5 FIG. 5 is a detail diagram of a diffraction pattern obtained by simulation according to an embodiment of the present application;
[0024] Figure 6 FIG. 6 is a simulation diagram of a diffraction pattern shifting with the displacement of a scale according to an embodiment of the present application.
[0025] Legend: 100-scale; 101-laser; 102-detector; 103-code channel; 104-reflective stripe; 105-transmissive stripe. DETAILED DESCRIPTION
[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.
[0027] The following detailed description of embodiments of the application in the drawings provided in the accompanying drawings is not intended to limit the scope of the application claimed, but merely represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.
[0028] It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, the terms "first", "second", "third" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.
[0029] In the description of the present application, it should also be noted that unless otherwise explicitly specified and limited, the terms "set", "mount", "connect", "connect" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0030] The commonly used photoelectric encoder at present is generally an image encoder. A code track 103 is formed on the scale 100, and a stripe structure with non-repeating pattern features is continuously formed on the code track 103. The image on the scale 100 is projected on the code reader in proportion through the irradiation of a non-coherent light source such as an LED, so that the absolute position of any position in a circle can be positioned. Since the stripe pitch of the code track is too small to cause diffraction effect, in the prior art, the amplitude and phase of the light waves emitted in all directions by the non-coherent light source such as an LED cannot be predicted, resulting in that the pattern after diffraction cannot be effectively detected. In addition, the divergence angle of the LED light source is relatively large, basically more than 45°, resulting in that a large amount of light is useless. Therefore, the LED light source needs a certain area to generate sufficient light power, otherwise the signal amplitude received by the detector 102 is not enough. Based on the above reasons, the stripe pitch density of the code track 103 in the prior art is difficult to reach below 10um, resulting in that the position accuracy and resolution of the encoder cannot be improved.
[0031] To solve the above technical problems, the embodiments of the present application provide a photoelectric encoder and a motor.
[0032] Reference Figure 1 , Figure 2As shown, the embodiment of the present application provides an optical encoder, which comprises a scale 100, a laser 101 and a detector 102; the scale 100 is provided with a code track 103, the code track 103 comprises a plurality of stripes distributed along the extension path of the scale 100 at intervals; when the scale 100 moves, the laser 101 emits light rays towards the code track 103, the light beam is diffracted towards the detector 102 through the stripes, the detector 102 receives the diffracted light, and the position information of the scale 100 can be obtained according to the position of the diffraction stripes.
[0033] It should be noted that the above-mentioned scale 100 can be a rotary code disc or a linear scale.
[0034] When the scale 100 is a rotary code disc, the code track 103 comprises a plurality of stripes distributed along the circumferential path of the code disc scale 100 at intervals;
[0035] It should be noted that the above-mentioned code track 103 can be an absolute code track or an incremental code track.
[0036] It should be noted that the scale 100 of the embodiment of the present application is provided with a plurality of stripes distributed along the extension path at intervals, and it should be noted that these stripes on the scale 100 constitute a unique pattern feature, so that each position has a unique code, thereby realizing absolute positioning. Compared with the prior art, the pitch of the stripes of the embodiment of the present application can be densely arranged, thereby improving the resolution and position accuracy of the encoder. Exemplarily, the stripe density of the embodiment of the present application is below 10 microns.
[0037] It should be noted that the embodiment of the present application adopts a single-mode laser 101 instead of a conventional incoherent light source, because the single-mode laser 101 has better beam quality and directivity. The single-mode energy ratio of the laser 101 in at least one direction is more than 40%, which ensures the high concentration and stability of the light beam and reduces the complex interference phenomenon that may be caused by multi-mode laser. The divergence angle of the laser 101 is much smaller than 45°, usually several degrees or even smaller, which means that more light can be concentrated in the target area, thereby improving the light energy utilization rate.
[0038] Exemplarily, the laser 101 of the embodiment of the present application comprises an edge-emitting laser 101.
[0039] When the light emitted by the single-mode laser 101 irradiates the code track 103 with fine and dense stripe structure, diffraction effect occurs, forming a series of diffraction stripes with alternating bright and dark. With the rotational movement of the scale 100, the diffraction stripes also move correspondingly. The detector 102 detects the position change of these diffraction stripes to accurately measure the position of the scale 100.
[0040] The technical effects that can be achieved by the embodiment of the present application are as follows:
[0041] The embodiment of the present application can achieve finer position division within a circle by using dense stripe spacing and high-quality laser light sources, and measuring the position of the scale 100 by detecting the position change of the diffraction stripes, thereby improving the accuracy of position measurement.
[0042] The detector 102 of the embodiment of the present application is used to receive light after the diffraction of the stripes of the scale 100, and accurately measure the position of the scale 100 by analyzing the position change of the diffraction stripes. Since the beam quality of the laser 101 is high, the detector 102 can receive stronger and clearer signals, reducing the influence of background noise and other interference factors, and improving the sensitivity and reliability of the system. Therefore, the detector 102 of the embodiment of the present application can more accurately analyze the position information.
[0043] Compared with the case of using a large-area high-power LED light source, the laser 101 can generate sufficient optical power in a smaller area, simplifying the physical design and manufacturing process of the system. In addition, this design of the embodiment of the present application is not only suitable for rotary encoders, but also can be extended to other types of motion sensors, providing greater flexibility and adaptability.
[0044] As an optional implementation, the detector 102 includes a plurality of subarray detection modules, each of which has a plurality of pixel blocks for receiving optical signals, and the plurality of pixel blocks are arranged along the movement direction of the stripes; the code track 103 is divided into a plurality of stripe bands, and the plurality of subarray detection modules correspond to the plurality of stripe bands one by one, and each subarray detection module detects a stripe band.
[0045] It should be noted that the detector 102 of the embodiment of the present application is composed of a plurality of independent subarray detection modules. Each subarray detection module is responsible for processing the optical signals in a specific region. Each subarray detection module includes a plurality of pixel blocks for receiving optical signals, and the pixel blocks are arranged along the rotation direction of the stripe band. The code track 103 of the embodiment of the present application is divided into a plurality of stripe bands, and each stripe band has a fine stripe structure. The plurality of subarray detection modules correspond to the plurality of stripe bands one by one, that is, each subarray detection module is responsible for detecting the diffraction stripe change on a stripe band.
[0046] It should be noted that when the scale 100 rotates, the light emitted by the laser 101 is incident on the stripe band on the scale 100 and is diffracted. Each subarray detection module independently detects the diffraction stripe change on the corresponding stripe band, and converts the information into an electrical signal. By analyzing these electrical signals, the system can accurately determine the position of the scale 100.
[0047] The technical effects that can be achieved by the embodiment of the present application are as follows:
[0048] Since each subarray detection module focuses on a small section of the fringe strip, it can allow these fringe strips to have a higher density, thereby improving the resolution and accuracy of the encoder. The uniform distribution of pixel blocks along the movement direction of the fringe ensures that the changing light signal can be captured uniformly during displacement, reducing errors caused by uneven pixel spacing and further improving measurement accuracy.
[0049] The multiple subarray detection modules process different sections of the fringe strip respectively, realizing distributed detection. In addition, the embodiments of the present application improve the reliability and stability of the overall system. If a subarray detection module fails, the remaining modules can still provide effective data to ensure continuous operation of the system.
[0050] Each subarray detection module works independently and detects the changes in the diffraction fringes from different fringe strips. This approach simplifies the signal processing process and reduces the complexity of the system. Since each subarray detection module only focuses on a specific section of the fringe strip, signal acquisition is more efficient, reducing unnecessary calculation and processing steps and improving the response speed and efficiency of the system.
[0051] More preferably, the detector 102 receives at least two pixel blocks within the pitch of the diffraction fringe for detecting the movement direction of the code track 103.
[0052] It should be noted that the embodiments of the present application set at least two pixel blocks within the same diffraction fringe pitch, which can use the phase difference between the light signals received by these pixel blocks to determine the movement direction of the code track 103. Specifically, when the scale 100 rotates, adjacent pixel blocks will receive diffraction fringes with alternating light and dark changes in turn. By comparing the time difference or intensity change of the signals received by these pixel blocks, the rotation direction of the scale 100 can be determined.
[0053] Compared with using only one pixel block, two or more pixel blocks can provide more information points within each fringe period, thereby improving the accuracy and reliability of position measurement.
[0054] In addition, the embodiments of the present application distribute multiple pixel blocks within the same diffraction fringe pitch, forming a redundant design. Even if a pixel block is disturbed or damaged, other pixel blocks can still work normally, ensuring the stability and reliability of the system.
[0055] It should be noted that the plurality of pixel blocks are arranged in the same diffraction fringe pitch, so that the system can realize the resolution improvement of the fringe period by more detailed analysis of the signal in each fringe period. For example, the original resolution can be improved by several times by processing the data of the plurality of pixel blocks through an interpolation algorithm. Therefore, the embodiment of the present application provides more sampling points through the plurality of pixel blocks, so that the system can more accurately measure the phase change of the diffraction fringe, thereby improving the accuracy of position measurement.
[0056] Referring to Figure 2 , as an optional embodiment, the fringes include reflective fringes 104; the laser 101 and the detector 102 are arranged on the same side of the scale 100, and the light emitted by the laser 101 is reflected and diffracted at the reflective fringes 104 and then enters the detector 102.
[0057] Referring to Figure 3 , as an optional embodiment, the fringes include transmissive fringes 105; the laser 101 and the detector 102 are arranged on the two sides of the scale 100 respectively, and the light emitted by the laser 101 transmits through the transmissive fringes 105 and then enters the detector 102.
[0058] As an optional embodiment, the pitch of the diffraction fringes is 1.6-2.5 times the distance between adjacent fringes on the code track 103.
[0059] Wherein, the distance from the laser 101 to the code track 103 is denoted as L1, and the distance from the detector 102 to the code track 103 is denoted as L2; wherein, the value range of (L1+L2) / L1 is 1.5-10.
[0060] Wherein, the distance between adjacent fringes on the code track 103 is less than 20 times the wavelength of the light.
[0061] It should be noted that the above parameters can be selected by those skilled in the art as needed, and the embodiment of the present application does not make special limitation thereto.
[0062] According to the Fresnel diffraction theory, the electric field at any point on the right receiving plate is the vector superposition of all light paths after distance attenuation. After traversing all light rays by the finite element method, the diffraction image on the right can be calculated, and the simulation results are shown in Figure 4 , Figure 5 and Figure 6 .
[0063] Wherein, Figure 4 is the overall distribution of the diffraction pattern; Figure 5 is the details of the diffraction pattern; Figure 6 is the displacement of the diffraction pattern with the displacement of the scale, and the four color curves in the figure are different by 1 / 8 of the grating pitch.
[0064] The embodiment of the present application provides a motor, which comprises a motor body and the photoelectric encoder.
[0065] The photoelectric encoder provided by the embodiment of the present application can be applied to the following technical fields in addition to the motor.
[0066] Angle sensor: used for measuring the angular position of rotating parts, such as the angular adjustment of astronomical telescopes, radar antennas and other equipment.
[0067] Linear displacement sensor: used for measuring the accurate position of linear motion parts, such as the position feedback in precision machine tools and automated production lines.
[0068] Robot joint control: used for accurately controlling the angle and position of robot joints, and improving the operation accuracy of the robot.
[0069] Medical equipment: such as surgical robots, imaging equipment and the like, which require high-precision position feedback to ensure the safety and accuracy of operation.
[0070] Aerospace: used for position and attitude monitoring in flight control systems to ensure the stability and safety of the aircraft.
[0071] It should be noted that the specific application scenarios of the photoelectric encoder described above can be set by those skilled in the art as needed, and no special limitation is made.
[0072] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Those skilled in the art can make various changes and modifications to the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A photoelectric encoder, characterized in that, It includes a scale, a laser, and a detector; the scale has a code track, which includes multiple stripes spaced apart along the extension path of the scale; when the scale moves, the laser emits light towards the code track, the light beam is diffracted through the stripes and emitted towards the detector, the detector receives the diffracted light, and can obtain the position information of the scale based on the position of the diffracted stripes.
2. The photoelectric encoder according to claim 1, characterized in that, The detector includes multiple sub-array detection modules, each having multiple pixel blocks for receiving optical signals, and the multiple pixel blocks are arranged along the movement direction of the stripes; the code track is divided into multiple stripe segments, and the multiple sub-array detection modules correspond one-to-one with the multiple stripe segments, with each sub-array detection module corresponding to one of the stripe segments.
3. The photoelectric encoder according to claim 2, characterized in that, The stripes include reflective stripes; the laser and the detector are located on the same side of the scale, and the laser beams emitted from the laser are reflected and diffracted at the reflective stripes before entering the detector.
4. The photoelectric encoder according to claim 2, characterized in that, The stripes include transmissive stripes; the laser and the detector are respectively disposed on both sides of the scale, and the laser beam passes through the transmissive stripes and then enters the detector.
5. The photoelectric encoder according to any one of claims 2-3, characterized in that, The detector receives diffraction fringes with at least two pixel blocks within the pitch, used to detect the movement direction of the code track.
6. The photoelectric encoder according to claim 5, characterized in that, The pitch of the diffraction fringes is 1.6-2.5 times the spacing between adjacent fringes on the code track.
7. The photoelectric encoder according to any one of claims 1-4, characterized in that, The distance from the laser to the code track is denoted as L1, and the distance from the detector to the code track is denoted as L2; wherein, the value of (L1+L2) / L1 ranges from 1.5 to 10.
8. The photoelectric encoder according to any one of claims 1-4, characterized in that, The spacing between adjacent stripes on the code track is less than 20 times the wavelength of light.
9. The photoelectric encoder according to any one of claims 1-4, characterized in that, The laser includes an edge-emitting laser.
10. An electric motor, characterized in that, It includes a motor body and a photoelectric encoder as described in any one of claims 1-9; the photoelectric encoder is installed in the motor body and is used to detect the rotational position of the motor.