An encoder and encoding method based on phase difference

Abstract

The application provides an encoder and an encoding method based on phase difference, wherein an encoder code disc is averagely divided into N shutter sectors and N-1 or N+1 infrared receiving lamp sectors; one shutter is arranged in each of the N-1 or N+1 shutter sectors, and the other shutter sectors are empty sectors; a plurality of infrared receiving lamps are sequentially arranged along the periphery of the arc of any infrared receiving lamp sector; an infrared light source with the center of the code disc as the center is arranged in the center of the code disc; the shutter is located between the infrared receiving lamp and the infrared light source; the method combining the infrared light source, the infrared receiving lamp and the shutter has the advantages of simple structure, low preparation cost and easy maintenance; and high-precision positioning and detection can be realized by averagely dividing the encoder code disc into N shutter sectors and N-1 or N+1 infrared receiving lamp sectors.

Description

Technical Field

[0001] This invention relates to the field of encoder design technology, and in particular to an encoder and encoding method based on phase difference. Background Technology

[0002] Glass code disks, as a mainstream form of optical encoder, use laser beams to identify the tracks on the glass code disk for positioning, offering high accuracy and stability. However, the tracks (also known as gratings or QR codes) on these code disks require precision machining techniques to fabricate. These techniques include photolithography, etching, coating, and polishing, and these processes must be performed in a cleanroom environment to ensure that the dimensions and surface quality of the tracks meet high-precision requirements. Therefore, the manufacturing process of this type of code disk is complex, resulting in relatively high production costs. Furthermore, since these code disks are made of glass, they are easily damaged, leading to higher maintenance costs. Summary of the Invention

[0003] The purpose of this invention is to provide an encoder and encoding method based on phase difference, which reduces the manufacturing and maintenance costs of the encoder and improves the reading accuracy of the encoder.

[0004] The present invention provides an encoder based on phase difference, comprising: N baffle sectors, N-1 or N+1 infrared receiving lamp sectors, baffles, infrared receiving lamp groups and infrared emitting sources;

[0005] The encoder disk is divided into N baffle sectors and N-1 or N+1 infrared receiving lamp sectors.

[0006] Each of the N baffle sectors is provided with a baffle, and the other baffle sector is an empty sector;

[0007] An infrared receiving lamp group is provided along the outer periphery of any of the infrared receiving lamp sectors, and the infrared receiving lamp group is provided with multiple infrared receiving lamps arranged at equal intervals.

[0008] The code disk is provided with an infrared light source centered on the center of the code disk.

[0009] The baffle is located between the infrared receiver and the infrared light source.

[0010] Furthermore, one end of the baffle is located inside the baffle sector, and the other end is located on the edge of the baffle sector.

[0011] Furthermore, the spacing between each pair of baffles is greater than the width of the light emitted by the infrared emitting source.

[0012] Furthermore, the arc length of the baffle is less than or equal to one-half of the arc length of the baffle sector.

[0013] Furthermore, the number of infrared receiving lamps set in any of the infrared receiving lamp sectors is greater than or equal to 3.

[0014] Furthermore, the angular difference between one infrared receiving lamp and the other infrared receiving lamp in any infrared receiving lamp group is 360 / (N-1)°-360 / N° or 360 / N-360 / (N+1)°.

[0015] Furthermore, a virtual infrared light is placed between each pair of infrared receiving lights.

[0016] Furthermore, the virtual infrared light is configured using at least one algorithm tool, including simulation software, algorithm libraries, and embedded systems.

[0017] Furthermore, the encoder can distinguish the smallest angular change in magnitude as (360 / (N-1)°-360 / N°) / w or (360 / N-360 / (N+1)°) / w;

[0018] Where w is the range of variation of each virtual infrared lamp in the analog-to-digital signal.

[0019] The present invention also provides an encoding method based on a phase difference encoder, which employs the aforementioned phase difference encoder.

[0020] Compared with the prior art, the present invention has at least the following technical effects:

[0021] This invention utilizes a combination of an infrared emitter, an infrared receiver, and baffles, resulting in a simple structure, low manufacturing cost, and ease of maintenance. Furthermore, by dividing the encoder disk into N baffle sectors and N-1 infrared receiver sectors, high-precision positioning and detection can be achieved. The N-1 infrared receiver sectors provide a transition between adjacent baffle sectors, helping to reduce errors and improve reading stability.

[0022] Furthermore, by virtually combining infrared lights, this invention can achieve more uniform and denser position detection coverage without increasing the actual number of receiving lights, thereby improving the reliability and stability of the system and obtaining more precise position detection. It also saves costs by eliminating the need for physically denser arrangement of receiving lights. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of an encoder based on phase difference in one embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of another structure of an encoder based on phase difference in one embodiment of the present invention. Detailed Implementation

[0025] The following description, with reference to schematic diagrams, illustrates a phase difference-based encoder and encoding method of the present invention, which represents a preferred embodiment of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0026] The invention is described more specifically by way of example in the following paragraphs with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0027] This embodiment provides a phase difference-based encoder, including: N baffle sectors, N-1 infrared receiving lamp sectors, baffles, infrared receiving lamp groups, and infrared emitting sources.

[0028] The encoder disk is divided into N baffle sectors and N-1 or N+1 infrared receiving lamp sectors.

[0029] Each of the N baffle sectors is provided with a baffle, and the other baffle sector is an empty sector; an infrared receiving lamp group is provided along the outer periphery of the arc of any infrared receiving lamp sector; multiple infrared receiving lamps are arranged at equal intervals within the infrared receiving lamp group; an infrared light source with the center of the code disk as the center is provided at the center of the code disk; the baffle is located between the infrared receiving lamp and the infrared emitting lamp.

[0030] This invention, through a combined design of an infrared emitter, infrared receiver, and baffles, eliminates the need for laser fabrication of the encoder's track, resulting in an encoder with a simple structure, low cost, and easy maintenance. Furthermore, by dividing the encoder code disk into N baffle sectors and N-1 or N+1 infrared receiver sectors, high-precision positioning and detection can be achieved. The N-1 or N+1 infrared receiver sectors provide a transition between adjacent baffle sectors, helping to reduce errors and improve readout stability.

[0031] Furthermore, the encoder disclosed in this embodiment operates as follows: When the code disk rotates, the infrared emitter continuously emits infrared light. The baffle alternately blocks and exposes the light source, causing changes in the intensity of the light detected by the infrared receiver, thereby generating high-pulse and low-pulse signals (a low-pulse signal is generated when the baffle blocks the light source that the infrared receiver can receive, and a high-pulse signal is generated when the baffle moves away). A high-precision signal processing algorithm is used to process the pulse signals to determine the time interval between two adjacent actual infrared receivers passing through the outer perimeter of any infrared receiver sector, thus calculating the rotational speed of the code disk. Combining the rotational speed of the code disk and the time interval traversed by the baffle, the angle of rotation of the code disk can be calculated.

[0032] In this embodiment, the number of infrared receiving lamp sectors and baffle sectors directly affects the encoder's resolution and accuracy. Theoretically, the more sectors of each type, the higher the resolution. However, too many sectors increase system complexity and affect the accuracy and stability of the code disk. Furthermore, too many sectors may increase manufacturing costs. Therefore, in actual manufacturing, the appropriate number of sectors needs to be selected based on specific requirements.

[0033] In one specific embodiment, the baffle sector has 16 sectors and the infrared receiving lamp sector has 15 sectors.

[0034] In another specific embodiment, the baffle sector has 14 sectors and the infrared receiving lamp sector has 16 sectors.

[0035] In this embodiment, one infrared receiver in the infrared receiver group is positioned close to the edge of the sector, while the remaining infrared receivers are arranged sequentially close to each other, with equidistant spacing between each pair of infrared receivers. Different infrared receiver groups are also equidistantly positioned. The uniform and equidistant arrangement of the infrared receiver groups, especially with one receiver positioned close to the edge of the sector, provides a precise starting reference point, thereby improving the system's resolution, reliability, and robustness, and simplifying the calibration process.

[0036] In this embodiment, the infrared receiving lamp is a photodiode. Those skilled in the art can select different types of infrared receiving lamps according to actual conditions.

[0037] Furthermore, the specific number of infrared receivers directly affects the encoder's resolution and accuracy. Theoretically, increasing the number of infrared receivers can improve measurement accuracy because more receivers provide finer angular resolution, allowing the encoder to detect minute positional changes. Multiple receivers also provide more light sources for detection, improving the uniformity and intensity of system illumination. However, too many infrared receivers lead to dense arrangement, affecting signal reception. Additionally, excessive infrared receivers increase design costs. Therefore, in actual manufacturing, the appropriate number of infrared receivers must be selected based on external factors such as sector size and manufacturing costs.

[0038] In one specific embodiment, an infrared receiving light group is provided with 3 infrared receiving lights.

[0039] The baffle in the code disk modulates the light beam emitted by the infrared emitter. By placing the baffle in the beam path, a specific light pulse pattern can be created.

[0040] In this embodiment, one end of the baffle is located inside the baffle sector, and the other end is located on the edge of the baffle sector. The specific arc length of the baffle should match the arc length of the code disk sector; that is, the longer the arc length of the code disk sector, the longer the specific arc length of the baffle, or the arc length of the code disk sector is proportional to the arc length of the baffle, in order to improve the accuracy and resolution of the code disk. However, the baffle should not be too large. If the baffle is too large, it may cause the infrared receivers of adjacent sectors to detect the baffle simultaneously, thereby reducing accuracy.

[0041] In a specific example, the arc length of the baffle is less than or equal to half the arc length of any baffle sector, and greater than one-third of the arc length. For example, assuming there are 16 baffle sectors, after determining the radius of the baffle sectors, the angle of each baffle sector is 22.5° (this angle refers to the angle formed by the two radii of the sector and the center point of the code disk being 22.5°). Then, the angle range of each baffle can also be set to 7.5°-12.25° (this angle range refers to the angle formed by the two ends of the baffle arc length and the center point of the code disk being 7.5°-12.25°). The arc length of the baffle is then set according to the angle of the baffle and the radius of the baffle sector.

[0042] In addition, the arc length of all the baffles in the code disk is generally set to be equal, so that the modulation of the beam by each baffle is uniform, which helps to generate consistent and predictable pulse signals.

[0043] Furthermore, the spacing between any two baffles needs to be greater than the width of the light emitted by the infrared emitter. If the spacing between the baffles is less than the beam width of the infrared emitter, the beam may overlap between adjacent baffles, resulting in a blurred signal received by the receiver and affecting the accuracy and resolution of the signal.

[0044] Furthermore, in this embodiment, the infrared emission source is arranged around the position of the code disk axis to emit infrared light.

[0045] In this embodiment, the infrared emission source is a circular infrared emission source with the center point of the code disk as the center, so that each infrared receiving lamp area on the code disk can receive infrared light, thereby improving the accuracy of reading.

[0046] In one specific embodiment, the infrared emitting source may include multiple emitting sources, such as multiple infrared LEDs evenly distributed along the circumference, with each LED emitting a beam of infrared light. Furthermore, the infrared emitting source may also include multiple infrared laser diodes, multiple infrared bulbs, or multiple infrared quantum dots, each of which can emit a beam of infrared light, ensuring that each infrared receiving area receives infrared light.

[0047] Furthermore, this embodiment also includes an empty sector. Due to the presence of this empty sector, by monitoring the scanning signals generated by the infrared emitter and receiver lamp within one revolution (i.e., one complete rotation cycle), the position of the baffle adjacent to the empty sector can be roughly identified, thereby improving the accuracy and reliability of angle measurement. Utilizing the presence of the empty sector and the scanning signals between infrared emission and reception, the position of the baffle can be effectively identified, improving the measurement accuracy of the code disk rotation angle.

[0048] In this embodiment, since the number of infrared receiving lamp sectors on the code disk is one more than the number of baffle sectors, there is an angle difference x° between two adjacent infrared lamps or between any infrared receiving lamp sector and its adjacent baffle sector. The magnitude of the angle difference x° is 360 / (N-1)°-360 / N° or 360 / N-360 / (N-1)°. That is, the angle difference between one infrared receiving lamp and the other infrared receiving lamp in any infrared receiving lamp group is 360 / (N-1)°-360 / N° or 360 / N-360 / (N+1)°. Due to limitations in physical space, it's impossible to place more infrared lamps in the actual equipment to improve resolution. Therefore, the angular difference x° can be used to virtually increase the number of infrared receivers. Specifically, virtual infrared receivers are placed around each actual infrared lamp at x° intervals. For example, an actual infrared receiver is placed at any position outside the arc of the infrared receiver's sector, and a virtual infrared receiver is placed x° to its left and x° to its right. This results in two virtual infrared receivers surrounding each actual infrared receiver. These virtual receivers can be a set of virtual positions obtained through calculation (i.e., positions x° away from the actual infrared receivers). These virtual positions simulate the function of the actual infrared receivers, allowing for measurement or detection at these locations.

[0049] In one specific embodiment, when there are 16 baffle sectors and 15 infrared receiving lamp sectors, and the angle difference between one infrared receiving lamp and another infrared receiving lamp in any infrared receiving lamp group is 1.5°, then a virtual receiving infrared lamp is set at the position of the 1.5° angle.

[0050] The virtual infrared receiver light is generated by an algorithm tool, which includes, but is not limited to, simulation software, algorithm libraries, and embedded systems.

[0051] Furthermore, if the range of change of the AD signal (the signal output by the analog-to-digital converter) of each infrared receiver lamp within the x° range is w (the resolution of the ADC, i.e., the smallest voltage change that the ADC can distinguish), then the theoretical design accuracy is x° / w (design accuracy refers to the closeness between the measured position value and the actual position value). The smaller the range of change of the AD signal w, the higher the theoretical accuracy. That is, the angle corresponding to each unit of change of the AD signal. For example, if the range of change of the AD signal of each infrared lamp within the x° range is 1mV, and x° is 1°, then the theoretical design accuracy is 1° / mV.

[0052] By virtually combining infrared lights, more uniform and denser location detection coverage can be achieved without increasing the number of actual receiving lights, thereby improving the reliability and stability of the system and obtaining more precise location detection. It also saves costs by eliminating the need for overly dense deployment of actual infrared receiving lights.

[0053] Please refer to Figure 1 The following example illustrates the possible structure of this encoder, with N=16, three infrared receiving lamps arranged sequentially around the outer arc of any infrared receiving lamp sector, and one infrared emitting source located at the position of the code disk shaft corresponding to any infrared receiving lamp sector:

[0054] There are 16 baffle sectors, each with a width of 22.5°; there are 15 infrared receiving lamp sectors, each with a width of 24°. 15 of the 16 baffle sectors are equipped with a baffle with an arc length of 11.25°, which is half the arc length of the baffle sector. In each infrared receiving lamp sector, an infrared receiving lamp is arranged every 6° (the angle difference between the midpoints of any two infrared receiving lamps is 6°). Three infrared receiving lamps are arranged sequentially around the outer edge of the arc of each infrared receiving lamp sector. One infrared emission source is arranged around the center of the code disk. There is an angle difference of 1.5° between any two adjacent infrared receiving lamps or any infrared receiving lamp sector and its adjacent baffle sector. Assuming the intensity change range of the baffle over each infrared lamp area by 1.5° is 8 digits 255, the final accuracy of this scheme is 1.5° / 255, approximately equal to 0.0059°.

[0055] Please refer to Figure 2 The following example illustrates the possible structure of this encoder, with N=14, three infrared receiving lamps arranged sequentially around the outer arc of any infrared receiving lamp sector, and one infrared emitting source located at the position of the code disk shaft corresponding to any infrared receiving lamp sector:

[0056] There are 14 baffle sectors, each with a width of 25.714°; there are 15 infrared receiving lamp sectors, each with a width of 24°. Thirteen of the 14 baffle sectors contain a baffle with an arc length of 12.875°, which is half the arc length of the baffle sector. In each infrared receiving lamp sector, an infrared receiving lamp is arranged every 6° (the angle difference between the midpoints of any two infrared receiving lamps is 6°). Three infrared receiving lamps are arranged sequentially around the outer edge of the arc of each infrared receiving lamp sector. One infrared emission source is arranged around the center of the code disk. The angle difference between any two adjacent infrared receiving lamps or any infrared receiving lamp sector and its adjacent baffle sector is 1.714°. Assuming the intensity change range of the baffle across each infrared lamp area is 1.714° with a range of 8 digits (255), the final accuracy of this scheme is 1.714° / 255, approximately 0.0067°.

[0057] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An encoder based on phase difference, characterized in that, include: N baffle sectors, N-1 infrared receiving lamp sectors, baffles, infrared receiving lamp groups, and infrared emitting sources; The encoder disk is divided into N baffle sectors and N-1 infrared receiving lamp sectors. Each of the N-1 baffle sectors is provided with a baffle, and the Nth baffle sector is an empty sector; An infrared receiving lamp group is provided along the outer periphery of any of the infrared receiving lamp sectors, and the infrared receiving lamp group is provided with multiple infrared receiving lamps arranged at equal intervals. The code disk is provided with an infrared light source centered on the center of the code disk. The baffle is located between the infrared receiver and the infrared light source.

2. The phase difference-based encoder as described in claim 1, characterized in that, One end of the baffle is located inside the baffle sector, and the other end is located on the edge of the baffle sector.

3. The phase difference-based encoder as described in claim 2, characterized in that, The distance between any two of the baffles is greater than the width of the light emitted by the infrared source.

4. The phase difference-based encoder as described in claim 3, characterized in that, The arc length of the baffle is less than or equal to one-half of the arc length of the baffle sector.

5. The phase difference-based encoder as described in claim 1, characterized in that, The number of infrared receiving lamps set in any of the infrared receiving lamp sectors is greater than or equal to 3.

6. The phase difference-based encoder as described in claim 1, characterized in that, The angular difference between one infrared receiving lamp and the other infrared receiving lamp in any infrared receiving lamp group is 360 / N-360 / (N-1)°.

7. The phase difference-based encoder as described in claim 1, characterized in that, A virtual infrared light is placed between each pair of infrared receiving lights.

8. The phase difference-based encoder as described in claim 7, characterized in that, The virtual infrared light is configured using at least one algorithm tool, including simulation software, algorithm libraries, and embedded systems.

9. The phase difference-based encoder as described in claim 8, characterized in that, The encoder can distinguish the smallest angle change magnitude as (360 / N-360 / (N-1)°) / w; Where w is the range of variation of each virtual infrared lamp in the analog-to-digital signal.

10. An encoding method based on a phase difference encoder, characterized in that, An encoder based on phase difference as described in any one of claims 1-9 is used.

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