A non-equidistant grating code disk and an absolute photoelectric shaft angle encoder

Abstract

This invention provides a non-equidistant grating code disk and an absolute photoelectric shaft angle encoder. The non-equidistant grating code disk includes a main grating with an equal grating angle and a slit grating with a non-equidistant grating angle. The slit grating has a split-phase window, which includes m reference grating lines and m gradually changing precision code grating lines arranged on both sides of the reference grating lines. The reference grating lines are positioned at the midpoint of the bright moiré fringes that are alternated between each other when moiré fringes are generated by the equal grating angle. Starting with the first reference grating line, the positions of the gradually changing precision code grating lines on both sides of the reference grating line are adjusted sequentially, so that the grating lines generating dark moiré fringes on adjacent sides of the reference grating line increase in an arithmetic sequence from an angle of 0°, gradually changing n times to the target grating angle. This invention, by designing the arrangement of the slit grating precision codes, makes the photoelectric signal extracted from the generated moiré fringes closer to the theoretical sine wave.

Description

Technical Field

[0001] This invention relates to the field of encoder technology, and more specifically, to a non-equidistant grating code disk and an absolute photoelectric shaft angle encoder. Background Technology

[0002] An optoelectronic encoder is a digital precision angle measurement device integrating opto-mechatronics. It uses a high-precision circular grating as the angular displacement reference, combining circular grating moiré fringe technology with photoelectric conversion technology to ultimately convert spatial angular displacement information into digital code and output it in real time. Due to its advantages such as high precision, high resolution, wide measurement range, reliable operation, long service life, and ease of maintenance, it is widely used in real-time control and dynamic measurement systems in aerospace, automatic control, radar, and other fields.

[0003] For traditional photoelectric shaft angle encoders that use moiré fringe signals for measurement, it is difficult to achieve the theoretical sinusoidal quality in extracting the original signal from the encoder. Suitable light source divergence angle, grating pitch, and grating gap are required. In a structure using one LED for illumination and one phototransistor for signal reception, a pair of LEDs can only extract one signal. Since photoelectric encoders typically have more than twenty signals, a large number of light-emitting devices are needed, and the correct phase relationship between each signal is required.

[0004] Simultaneously performing phase adjustment on more than twenty signals is cumbersome and time-consuming. Furthermore, it suffers from various problems, such as signal instability caused by the combined influence of multiple light sources. Summary of the Invention

[0005] The purpose of this invention is to provide a non-equidistant grating code disk and an absolute photoelectric shaft angle encoder, which can solve at least one of the aforementioned technical problems. The specific solution is as follows:

[0006] According to specific embodiments disclosed in this invention, the first aspect of this invention discloses a non-equidistant grating code disk, comprising: a main grating with an equidistant grating angle and a slit grating with a non-equidistant grating angle;

[0007] The slit grating has a split-phase window, which includes: m reference grating lines and m gradient precision code grating lines disposed on both sides of the reference grating lines.

[0008] The reference grating lines are set at the midpoint of every other bright or dark moiré fringe when the moiré fringes are generated by the equal grating pitch angle.

[0009] Starting with the first reference grating line, the positions of the gradient precision grating lines on both sides of the reference grating line are adjusted sequentially, so that the grating lines that produce dark moiré fringes or bright moiré fringes on adjacent sides of the reference grating line increase in an arithmetic sequence from an angle of 0°, and after multiple gradients, they reach the target grating pitch angle.

[0010] Optionally, the number of gradients n is equal to the number of reference grating lines m.

[0011] Optionally, the slit grating split-phase window further includes: fine code grating lines with equal grating pitch angles located at both ends of the slit grating split-phase window, wherein the number of the gradient fine code grating lines is at least half the number of the fine code grating lines with equal grating pitch angles.

[0012] Optionally, the angle between the gradient precision code grating lines that generate dark moiré fringes or bright moiré fringes on adjacent sides of the reference grating line and the reference grating line is equal.

[0013] According to specific embodiments disclosed in this invention, a second aspect of this invention discloses an absolute shaft angle photoelectric encoder, comprising:

[0014] The aforementioned non-equidistant grating code disk is used to generate moiré fringes;

[0015] Multiple receiving devices are arranged on one side of the non-equidistant angle grating code disk to detect the moiré fringes generated in each channel and output multiple fine code photoelectric signals.

[0016] A light source assembly is disposed on the other side of the non-equidistant angle grating code disk, such that the illumination area of ​​a beam of parallel light generated by the light source assembly covers the receiving area of ​​the plurality of receiving devices.

[0017] The signal processing circuit extracts the precise photoelectric signals from the multiple receiving devices.

[0018] Optionally, the light source assembly includes: an infrared point light source and a beam shaping mirror, wherein the beam shaping mirror is a spherical lens or an aspherical lens;

[0019] The infrared point source and the beam shaping mirror satisfy a matching relationship:

[0020] R = tanθ × f

[0021] Where R is the radius of the beam shaping mirror, and f is the focal length of the beam shaping mirror;

[0022] θ is the half-divergence angle of the infrared point light source.

[0023] Optionally, the lens is an aspherical lens, and the image plane relationship satisfies: BFL@587.6nm is 15.19mm.

[0024] Optionally, the grating gap of the non-equidistant grating code disk is ≥0.3mm.

[0025] Optionally, the photoelectric signal contrast ratio is >3.

[0026] Compared with the prior art, the solutions disclosed in this invention have at least the following beneficial effects:

[0027] This invention forms moiré fringes by using a slit grating with a gradually varying grating pitch angle to form precise codes. This makes the sinusoidal nature of the photoelectric signal extracted from the moiré fringes closer to the theoretical sine, thus relaxing the strict restrictions on the divergence angle of the light source and the grating gap during the design and assembly stages.

[0028] By employing a one-to-many illumination method where one photoelectric transmitter corresponds to multiple receivers, the photoelectric shaft angle encoder can be assembled and adjusted without strictly matching the phase of each signal, thus improving assembly and adjustment efficiency. Furthermore, the use of a non-uniform grating code disk allows the encoder to have a larger grating gap and stronger photoelectric signal contrast. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure of this invention and, together with the description, serve to explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0030] Figure 1 a is a schematic diagram of the grating line distribution at the phase splitting point of a non-equidistant grating code disk slit grating provided in an embodiment of the present invention;

[0031] Figure 1 b is Figure 1 a. Enlarged view of both ends;

[0032] Figure 2 The waveform of the moiré fringe signal extracted from the equidistant grating code disk;

[0033] Figure 3 The Lissajous circle generated from the photoelectric signal measured by the non-equidistant slit grating provided in the embodiments of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of an absolute shaft angle photoelectric encoder provided in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of a current technology where the photoelectric light-emitting device and the receiving device are set up in a one-to-one configuration.

[0036] Figure 6 This is a schematic diagram of a multi-position configuration of a photoelectric light-emitting device and a receiving device provided in an embodiment of the present invention;

[0037] Figure 7 Photoelectric signal contrast diagram of Embodiment 1 of the present invention;

[0038] Figure 8 This is a photoelectric signal contrast diagram of Embodiment 2 of the present invention;

[0039] Figure 9 This is a comparison chart of static accuracy test results from Embodiment 1 of the present invention;

[0040] Figure 10 This is a comparison chart of dynamic accuracy test results from Embodiment 2 of the present invention.

[0041] Figure label:

[0042] 1-Infrared point source; 2-Beam shaping mirror; 3-Non-equidistant grating code disk; 4-Receiver device. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, a device for extracting photoelectric signals from an absolute encoder, as disclosed in this invention, will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments disclosed in this invention, and not all of them. Based on the embodiments disclosed in this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the application. The singular forms “a,” “said,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0045] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0046] It should be understood that although the terms first, second, third, etc., may be used to describe embodiments of this application, these terms should not be used in isolation. These terms are only used to distinguish between different terms. For example, first may also be referred to as second without departing from the scope of embodiments of this application, and similarly, second may also be referred to as first.

[0047] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the article or device that includes said element.

[0048] The following is in conjunction with the appendix Figure 1-10 Detailed description of optional embodiments of the present invention.

[0049] like Figure 1 As shown in the figure, according to a specific embodiment of the present invention, the first aspect of the present invention provides a non-equidistant grating code disk, comprising: a main grating with an equidistant grating angle and a slit grating with a non-equidistant grating angle.

[0050] The core design parameters of photoelectric shaft angle encoders include final resolution and accuracy. After knowing the mechanical diameter of the encoder and the area of ​​the receiver, the initial settings of the grating pitch angle and the number of grating lines of the main grating and slit grating in the grating code disk can be made.

[0051] Specifically, the base resolution and subdivision factor are determined by the final resolution. The number of coarse code lines in the main grating is determined based on the base resolution, and the grating pitch angle of the main grating can be calculated based on the number of coarse code lines. In this embodiment, the main gratings have equal grating pitch angles.

[0052] The slit grating code track has four phase-splitting windows with phase differences between them, and a code grating line is arranged at each phase-splitting window. In this embodiment, the code grating lines at the phase-splitting windows can be divided into: reference grating lines, gradient code grating lines, and equidistant code grating lines with equal grating pitch angles.

[0053] According to the principle of moiré fringe formation, the period of the slit grating should be equal to the period of the main grating. Therefore, when designing a gradient grating pitch angle for the slit grating, the pitch angle of two adjacent pairs of fine code grating lines is a fixed value, which is the pitch angle of the main grating. After determining the pitch angle, the number of fine code grating lines in the slit grating is further determined by the area of ​​the receiver. In this embodiment, two adjacent pairs of fine code grating lines refer to the fine code grating lines that produce two pairs of alternating bright and dark moiré fringes.

[0054] Furthermore, after determining the number of precision code grating lines in each split-phase window, the position of the reference grating grating lines is determined. All precision code grating lines can be selected as gradient precision code grating lines for gradient pitch design, or a portion of the precision code grating lines can be selected for gradient design, thereby determining the gradient number n.

[0055] Specifically, completing n gradient transitions to a fixed target grating pitch angle requires adjusting the positions of 2m precision code grating lines. Therefore, m reference grating lines and 2m gradient precision code grating lines are needed.

[0056] In this embodiment, the reference grating line is the midpoint of every alternate Mink moiré fringe generated at equal grating pitch angles. That is, the midpoints of the nth, (n+2nd), (n+4th), ... Mink moiré fringes are used as the reference grating lines. Figure 1 In (b), positions a and b are reference grating lines.

[0057] Using the first reference grating line at position a as the adjustment reference, the gradient precision grating lines on both sides of the reference grating line are changed sequentially so that the angle between the dark moiré fringes generated on the left side of position a and the dark moiré fringes generated on the right side of position a is 0°. Therefore, no reference grating line is actually etched at position a.

[0058] Next, adjust the positions of the gradient precision code grating lines that generate dark moiré fringes on both sides of the second reference grating line at position b, so that the included angle increases in an arithmetic progression until the included angle of the dark moiré fringes generated on both sides of the m-th reference grating line returns to the target grating pitch angle in degrees, with the grating pitch angle of the main grating as the target grating pitch angle. At this point, the precision code grating pitch that generates the dark moiré fringes remains unchanged, and the precision code grating pitch that generates the dark moiré fringes increases in an arithmetic progression.

[0059] In other embodiments, the code line that produces dark moiré fringes can be used as the reference code line, and the code pitch that produces bright moiré fringes can be adjusted to achieve the design of a non-equidistant grating code disk.

[0060] Furthermore, in other embodiments, at least half or two-thirds of the precision code grating lines in the middle of the split-phase window are selected for a gradient grating pitch design. The precision code grating lines at both ends of the split-phase window are retained at a fixed grating pitch angle consistent with the main grating, which serves to homogenize the image and improve the fitting effect.

[0061] The design method of the present invention will be described below through an embodiment.

[0062] According to the design specifications, the main grating is arranged with 8192 coarse code grating lines around its entire circumference. Therefore, the grating pitch angle of each coarse code grating line pair is 0.0439453125°.

[0063] Based on the area of ​​the receiver, 60 pairs of precision code grating lines are drawn in the slit grating corresponding to the precision code area, and the grating pitch angle of each precision code grating line pair is 0.0439453125°. Therefore, the included angle of the precision code grating lines that produce two dark moiré fringes, which is also the included angle of the light-blocking part, is 0.02197265625°.

[0064] Without a non-uniform grating design, the waveform obtained by extracting the moiré fringe signal using parallel light source illumination will be an irregular waveform between a triangular wave and a sine wave. For example... Figure 2 As shown.

[0065] Figure 1 Figure 'a' shows a schematic diagram of the grating lines drawn when 60 pairs of grating lines are drawn in the grating area of ​​this embodiment. The 40 pairs of grating lines in the middle area of ​​the figure are located in a gradient area with non-equidistant grating pitch, i.e., the gradient number is 20. Ten pairs of grating lines with equal grating pitch are drawn at each end.

[0066] Specifically, such as Figure 1 As shown in b, the lines of the 11th-12th light-blocking section are joined together, forming an angle of 0°. The angle between the lines of the 13th-14th light-blocking section becomes 0.0010986328125°, and so on. After 20 transformations, the angle between the 39th-40th black lines is restored to 0.02197265625°.

[0067] Figure 3 It can be seen that by using a gradually varying grating pitch to incorporate more diffraction, the quality of the acquired original photoelectric signal is higher, and the quality of the Lissajous circle is also higher, meaning better orthogonality and roundness. This results in higher angular measurement accuracy after subsequent subdivision. Consequently, the strict limitations on the light source divergence angle and grating gap during the design and assembly stages can be relaxed, which is beneficial for enhancing the contrast of the photoelectric signal and improving the accuracy of encoder photoelectric signal extraction.

[0068] Therefore, as Figure 4 As shown, a second aspect of the present invention provides an absolute photoelectric shaft angle encoder, comprising:

[0069] Non-equidistant grating code disk 3 generates moiré fringes on multiple channels;

[0070] Multiple receiving devices 4 are set on one side of the non-equidistant angle grating code disk 3 to detect the moiré fringes generated in each channel and output multiple fine code photoelectric signals.

[0071] A light source assembly is disposed on the other side of the non-equidistant angle grating code disk 3, so that the illumination area of ​​a beam of parallel light generated by the light source assembly covers the receiving area of ​​the plurality of receiving devices 4.

[0072] The signal processing circuit extracts the precise photoelectric signals from the plurality of receiving devices 4.

[0073] Traditional transmissive photoelectric encoders use a signal extraction method where one LED corresponds to one phototransistor to receive the photoelectric signal, meaning that a pair of LED receivers can only extract one photoelectric signal. Whether for a single-turn or multi-turn absolute encoder, to record more absolute positions, at least ten channels are typically required, and the position of each LED must be strictly calibrated to ensure signal phase relationships.

[0074] Meanwhile, due to the large divergence angle of a single infrared point light source, in order to achieve high extraction accuracy, in addition to using optical subdivision and interpolation to reduce the number of channels, the slit grating needs to have a large precision code pitch and a small grating gap with the main grating. However, a large precision code pitch directly leads to an increase in the diameter of the grating code disk, making the resolution limited by the physical size of the code disk. On the other hand, the design of a small grating gap is sensitive to code disk eccentricity and vibration, and is prone to failure due to wear or thermal deformation during long-term operation. It can also easily cause the main grating and the slit grating to rub against each other. Therefore, the absolute photoelectric shaft angle encoder in this embodiment relaxes the strict limitation on the grating gap by using a non-equidistant grating angle grating code disk 3. On the other hand, it adopts a one-to-many illumination method with one photoelectric transmitter corresponding to multiple receivers, thereby enhancing the contrast of the photoelectric signal. Furthermore, when assembling and adjusting the photoelectric shaft angle encoder, it is not necessary to strictly match the phase of each signal, thus improving the assembly and adjustment efficiency.

[0075] Specifically, the light source assembly includes: an infrared point light source 1 and a beam shaping mirror 2. The beam shaping mirror 2 shapes the beam emitted by the infrared point light source 1 into a parallel beam capable of covering the receiving area of ​​multiple receiving devices 4.

[0076] Furthermore, for rotating absolute grating code disks, spherical or aspherical mirrors can be used to generate highly uniform circular light spots that can cover the slit grating split-phase window region.

[0077] When a spherical lens or an aspherical lens is selected, the infrared point light source 1 is positioned at the focal point of the beam shaping mirror 2, and has the following positional relationship with the lens:

[0078] R = tanθ × f.

[0079] Where R is the radius of the lens, and f is the focal length of the lens;

[0080] θ is the half-divergence angle of the infrared point light source.

[0081] This invention, by using a single infrared point light source in conjunction with a lens system, ensures the consistency of the optical path in each channel, directly generating phase-aligned A / B phase signals. Furthermore, using only a single infrared point light source avoids the signal instability caused by the combined influence of multiple light sources, which is common when using multiple light sources, thus improving the contrast of the photoelectric signal.

[0082] Traditional photoelectric encoders have LEDs with large divergence angles. These large divergence angles necessitate larger precision code pitches and smaller grating gaps. The following equation exists to express the relationship between photoelectric signal contrast and grating gap:

[0083] t = nP 2 / λ.

[0084] Where t represents the photoelectric signal contrast ratio and P represents the grating pitch;

[0085] n is an integer, and λ is the grating gap.

[0086] Analysis of the above formulas shows that a smaller grating gap λ results in a stronger photoelectric signal contrast t. While reducing the grating gap can enhance photoelectric signal contrast, an excessively small gap increases the risk of mechanical interference between the main grating and the slit grating. Conversely, an excessively large grating pitch leads to enhanced light diffraction, particularly for high-density gratings, resulting in decreased photoelectric signal contrast. Furthermore, due to the limitations of the grating code disk's mechanical dimensions, the number of grating line pairs in the precision code grating decreases, leading to reduced moiré fringe contrast and affecting measurement accuracy.

[0087] The grating gap range of existing absolute photoelectric encoders is generally 0.15-0.22mm, with an allowable eccentricity between ±5 and ±15μm, corresponding to an assembly difficulty level of 3-4. Meanwhile, the photoelectric signal contrast decreases as the gap increases; the best photoelectric signal contrast achievable within this grating gap range is 2.5.

[0088] The absolute photoelectric shaft angle encoder of this embodiment can increase the grating gap between the main grating and the slit grating to 0.3mm, which not only reduces the assembly difficulty level, but also reduces the diameter of the grating code disk and improves the photoelectric signal contrast to greater than 3.

[0089] In one embodiment of the invention, a point infrared light source with a wavelength of 890 nm and a divergence angle of 50° is selected for illumination. An aspherical lens is selected as the beam shaper; at a wavelength of 587.6 nm, the distance between the back focal length of the aspherical lens and the receiving device is 15.19 mm, i.e., BFL@587.6 nm is 15.19 mm. In other embodiments, a spherical lens can also be used for beam shaping to generate a parallel beam with a circular spot capable of covering the grating code disk.

[0090] like Figure 5 As shown, the area enclosed by the red lines is the illumination area formed on the grating code disk after the infrared point light source is collimated by the aspherical lens. The multiple areas enclosed by the yellow lines are the receiving areas of each receiving device. The area of ​​the red coil covers the entire area of ​​the yellow region. Within the area formed by the red coil, this embodiment sets up 12 receiving devices according to the specific arrangement of the precision code grating lines. The distance between the plane where the receiving devices are located and the slit grating is 0.5 mm.

[0091] Figure 6 In contrast to this embodiment, the prior art uses a one-to-one configuration for the light-emitting receiver devices. The illumination area formed by each point light source on the light spot code disk should cover the receiving area of ​​each receiver device accordingly. Therefore, there are problems such as difficulty in assembly and adjustment and mutual interference among multiple point light sources.

[0092] The absolute photoelectric shaft angle encoder of this embodiment was tested, and the results are as follows:

[0093] Figures 7-8 This is a test graph showing the axial angle photoelectric signal contrast obtained in this embodiment with 12 receiving devices but at different grating gaps. The horizontal axis represents the number of sampling points; the vertical axis represents the numerical value of the photoelectric signal contrast.

[0094] Example 1

[0095] The grating gap is 0.30mm, and the photoelectric signal contrast is approximately 9.

[0096] Example 2

[0097] The grating gap is 0.35mm, and the photoelectric signal contrast is approximately 8.

[0098] Figures 9-10 The test diagrams for Examples 1 and 2 show that, compared to traditional photoelectric shaft angle encoders, this example increases the overall accuracy of the system and improves the static and dynamic accuracy error values ​​of the photoelectric shaft angle encoder. The static accuracy improves from... Figure 9 (b) 2.12″ decreased to Figure 9 (a) 0.75″, improved by at least 1″, dynamic accuracy error value from Figure 10 (a) decreased by 40 to Figure 10 (b) 10 code values.

[0099] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0100] The above embodiments are only used to illustrate the technical solutions disclosed in this invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments disclosed in this invention.

Claims

1. A non-equal-lattice-angle optical grating code disc, characterized by, The non-equal grating spacing angle grating scale includes: a main grating with equal grating spacing angle and a slit grating with non-equal grating spacing angle; the slit grating has a split phase window, and the split phase window includes m reference grating lines and m gradually changed fine code grating lines arranged on both sides of the reference grating lines; the reference grating lines are arranged at the midline positions of every other bright or dark Moiré fringe generated by the equal grating spacing angle; starting from the first reference grating line, the positions of the gradually changed fine code grating lines on both sides of the reference grating line are sequentially adjusted, so that the grating lines on both sides of the reference grating line generating dark Moiré fringes or bright Moiré fringes increase by equal difference from an included angle of 0° to a target grating spacing angle through multiple gradual changes.

2. The non-equal-pitch angular grating code disc of claim 1, wherein, The number of gradual changes n is equal to the number m of the reference grating lines.

3. The non-equal-pitch angular grating code disc of claim 2, wherein, The slit grating split phase window further includes fine code grating lines with equal grating spacing angle at both ends of the slit grating split phase window, and the number of the gradually changed fine code grating lines is at least half of the number of the fine code grating lines with equal grating spacing angle.

4. The non-equal grating spacing angle grating scale according to claim 2, the included angle of the gradually changed fine code grating lines on both sides of the reference grating line generating dark Moiré fringes or bright Moiré fringes is equal to that of the reference grating line.

5. An absolute optical shaft angle encoder, characterized in that The non-equal grating spacing angle grating scale includes: the non-equal grating spacing angle grating scale according to any one of claims 1-4, used for generating Moiré fringes; a plurality of receiving devices arranged on one side of the non-equal grating spacing angle grating scale, respectively detecting Moiré fringes generated by each channel and outputting a plurality of fine code photoelectric signals; a light source assembly arranged on the other side of the non-equal grating spacing angle grating scale, so that the irradiation area of a parallel light generated by the light source assembly covers the receiving area of the plurality of receiving devices; a signal processing circuit for extracting the fine code photoelectric signals of the plurality of receiving devices.

6. The absolute opto-electric shaft angle encoder according to claim 5, characterized in that The light source assembly includes an infrared point light source and a beam shaping mirror, and the beam shaping mirror is a spherical lens or an aspherical lens. The infrared point light source and the beam shaping mirror satisfy a matching relationship: R = tanθ × f wherein R is the radius of the beam shaping mirror, f is the focal length of the beam shaping mirror, and θ is the half divergence angle of the infrared point light source. The lens is an aspherical lens, and the image surface relationship satisfies: BFL@587.6nm is 15.19mm.

7. The absolute opto-electric shaft angle encoder according to claim 6, characterized in that The grating gap of the non-equal grating spacing angle grating scale is greater than or equal to 0.3mm.

8. The absolute opto-electric shaft angle encoder according to claim 5, characterized in that The photoelectric signal contrast is greater than 3.

9. The absolute opto-electric shaft angle encoder according to claim 5, characterized in that ​

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