Reflective absolute value encoder

Abstract

The application provides a reflective absolute value encoder, relates to the technical field of photoelectric encoders, and comprises a code disc, a substrate and a differential processing unit. The code disc is disc-shaped, and two absolute code channels are concentrically arranged. The absolute code channels are both composed of a plurality of reflection zones and non-reflection zones arranged alternately, and the positions of the reflection zones and the non-reflection zones of the two absolute code channels are opposite. The substrate is parallel to the code disc, and a light source and two absolute light-receiving arrays are arranged on the side facing the code disc. The two absolute light-receiving arrays receive reflected light of the corresponding absolute code channels respectively. The differential processing unit is electrically connected with the two absolute light-receiving arrays, and performs differential operation on the electrical signals generated by the two absolute light-receiving arrays. The application can effectively suppress common-mode noise, reduce the influence of external interference on the measurement results, and make the encoder output more stable.

Description

Technical Field

[0001] This utility model relates to the field of photoelectric encoder technology, and in particular to a reflective absolute encoder. Background Technology

[0002] Traditional reflective photoelectric encoders are based on optical imaging principles, generating moiré fringes by superimposing a code disk and a slit disk. This characteristic allows them to tolerate variations in the gap between the code disk and the slit, and they can be illuminated using a simple diffuse reflection light source. However, this approach has inherent limitations: to achieve high-resolution absolute value measurement, dozens of code tracks are typically required. This not only directly leads to a complex and larger code disk and readhead structure, but also presents the challenge of precisely controlling the outgoing light angle in reflective optical paths. Existing reflective absolute value code disks require measuring the average light intensity on the absolute light-receiving array to determine the signal switching potential. However, the light intensity distribution design may differ from actual conditions. Furthermore, considering that the light source itself decays with use and the output light intensity fluctuates with temperature, affecting the amount of light received on the light-receiving array and thus causing unstable output signals, the application range and scenarios of the encoder are limited. Utility Model Content

[0003] To address the problems in the background technology, this utility model aims to provide a more user-friendly reflective absolute encoder that can be used in different environments and is less affected by changes in light intensity, thereby reducing the impact of external interference on measurement results and improving the stability and applicability of the encoder.

[0004] To achieve the above objectives, this utility model provides a reflective absolute encoder, including a code disk, a substrate, and a differential processing unit.

[0005] The code disk is disc-shaped with two absolute code tracks arranged concentrically. Each absolute code track consists of several reflective and non-reflective areas arranged alternately, and the positions of the reflective and non-reflective areas of the two absolute code tracks are opposite.

[0006] The substrate is parallel to the code disk, and a light source and two absolute light-receiving arrays are provided on the side facing the code disk. The two absolute light-receiving arrays respectively receive the reflected light of the corresponding absolute code track.

[0007] The differential processing unit is electrically connected to two absolute light-receiving arrays and performs differential operations on the electrical signals generated by the two absolute light-receiving arrays.

[0008] Furthermore, it also includes a first incremental code track and a second incremental code track concentrically arranged on the code disk, and two incremental light-receiving arrays correspondingly arranged on the substrate, the two incremental light-receiving arrays receiving the reflected light from the first incremental code track and the second incremental code track respectively.

[0009] Furthermore, the first incremental code track is disposed inside the second incremental code track, and the spacing between the reflective parts of the first incremental code track is twice the spacing between the reflective parts of the second incremental code track.

[0010] Furthermore, the absolute code channels are all located inside the first incremental code channel and the second incremental code channel, and the absolute light-receiving arrays are all located inside the incremental light-receiving arrays; the light source is located between the two incremental light-receiving arrays.

[0011] Furthermore, the absolute light-receiving array includes strip-shaped C+ light-receiving elements and C- light-receiving elements, which respectively receive reflected light from two absolute code channels. The C- light-receiving element is positioned on the side closer to the center of the circle relative to the C+ light-receiving element; the upper and lower edges of the C+ light-receiving element are both arc-shaped.

[0012] Furthermore, the length of the C- light-receiving element along the radial direction is greater than the length of the C+ light-receiving element.

[0013] Furthermore, the lower edge of the C- light-receiving element is a quadratic function curve, so that the C- light-receiving element receives the same amount of light as the C+ light-receiving element.

[0014] Furthermore, each incremental light-receiving array consists of several groups of incremental light-receiving elements, each group containing 4 incremental light-receiving elements, and adjacent incremental light-receiving elements are 90° out of phase for relative position counting.

[0015] Furthermore, the incremental light-receiving element has a harmonic filtering profile.

[0016] Furthermore, the light source is a monochromatic point light source.

[0017] Compared to existing technologies, this invention offers the following advantages: By setting two absolute code tracks with opposite positions for the reflective and non-reflective areas, the electrical signals generated by the corresponding absolute light-receiving arrays exhibit complementary characteristics. Furthermore, through differential processing, common-mode noise is effectively suppressed. Only the positive or negative sign of the signal is needed to determine the absolute position, effectively reducing errors caused by unstable changes in the light source. There is no need to detect the average light intensity on the absolute light-receiving array or determine the signal switching potential before use, thereby improving the encoder's ease of use, reducing the impact of external interference on measurement results, enhancing reliability in harsh environments, and making the output more stable. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the encoder structure in an embodiment of the present invention;

[0019] Figure 2 This utility model Figure 1 An enlarged schematic diagram of the middle section;

[0020] Figure 3 This is a schematic diagram of the substrate structure in an embodiment of the present invention.

[0021] Wherein, 1: code disk; 2: substrate; 3: absolute code track; 4: light source; 5: absolute light-receiving array; 6: first incremental code track; 7: second incremental code track; 8: incremental light-receiving array; 31: reflective area; 32: non-reflective area; 51: C+ light-receiving element; 52: C- light-receiving element. Detailed Implementation

[0022] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly. The connection can be a direct connection or an indirect connection.

[0025] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0026] Reference Figures 1 to 3 The reflective absolute encoder provided in one embodiment of the present invention includes a code disk 1, a substrate 2, and a differential processing unit.

[0027] like Figure 1 and Figure 2 The diagram shown is a schematic diagram of the structure of the code disk 1 in this embodiment. The code disk 1 is disc-shaped and has two absolute code tracks 3 arranged concentrically. Each absolute code track 3 is composed of several reflective areas 31 and non-reflective areas 32 arranged alternately. The positions of the reflective areas 31 and non-reflective areas 32 of the two absolute code tracks 3 are opposite.

[0028] The code disk 1 uses two concentric absolute code tracks 3, and the reflective area 31 and non-reflective area 32 of the two absolute code tracks 3 are in opposite positions. When one absolute code track 3 is in the reflective area 31, the other absolute code track 3 is in the non-reflective area 32, thereby generating complementary optical signals.

[0029] like Figure 3 As shown, this is a schematic diagram of the structure of the substrate 2 in this embodiment. The substrate 2 is parallel to the code disk 1, and a light source 4 and two absolute light receiving arrays 5 are provided on the side facing the code disk 1. The two absolute light receiving arrays 5 respectively receive the reflected light of the corresponding absolute code track 3.

[0030] The substrate 2 is provided with a light source 4 and two absolute light-receiving arrays 5. The positions of the two absolute light-receiving arrays 5 correspond to the two code channels respectively, and are used to receive the reflected light generated by the two absolute light-receiving arrays 5 and convert it into electrical signals.

[0031] The differential processing unit is electrically connected to the two absolute light-receiving arrays 5 and performs differential operations on the electrical signals generated by the two absolute light-receiving arrays 5.

[0032] The differential processing unit can be a differential amplifier circuit or other component capable of performing differential operations on the electrical signals generated by the two absolute light-receiving arrays 5. Through differential operations, the differential processing unit can effectively suppress common-mode noise, significantly reduce the impact of external interference on the measurement results, and improve the reliability of the encoder in harsh environments. Differential operations not only suppress noise but also amplify the effective signal. Only the positive or negative sign of the signal needs to be used to determine the absolute position, which can effectively reduce errors caused by unstable changes in the light source 4, making position detection more accurate and enabling more detailed angle or position measurements.

[0033] In summary, this embodiment sets two absolute code tracks 3 with opposite positions for the reflective area 31 and the non-reflective area 32, so that the electrical signals generated by the corresponding absolute light-receiving array 5 have complementary characteristics. Furthermore, through differential processing unit operations, common-mode noise can be effectively suppressed. Only the positive or negative sign of the signal is needed to determine the absolute position, effectively reducing errors caused by unstable changes in the light source 4. There is no need to detect the average light intensity on the absolute light-receiving array and determine the signal switching potential before use, thereby improving the encoder's ease of use, reducing the impact of external interference on measurement results, enhancing reliability in harsh environments, and making the output more stable.

[0034] In this embodiment, the reflective absolute encoder further includes a first incremental code track 6 and a second incremental code track 7 concentrically arranged on the code disk 1, and two incremental light receiving arrays 8 correspondingly arranged on the substrate 2, the two incremental light receiving arrays 8 receiving the reflected light from the first incremental code track 6 and the second incremental code track 7 respectively.

[0035] Among these features, setting incremental code tracks can improve encoder resolution by calculating the number of pulses to measure relative displacement.

[0036] In this embodiment, the first incremental code track 6 is disposed inside the second incremental code track 7, and the spacing of the reflective parts of the first incremental code track 6 is twice the spacing of the reflective parts of the second incremental code track 7.

[0037] The incremental code track has equally spaced striped reflective sections of the same width along the measurement direction, used to generate periodic signals. Two incremental code tracks can generate two incremental signals with a 90° phase difference. The combination of these two signals can be used to determine the direction of rotation and can compensate for the absolute position, further improving the resolution.

[0038] In this embodiment, the absolute code track 3 is disposed inside the first incremental code track 6 and the second incremental code track 7, and the absolute light receiving array 5 is disposed inside the incremental light receiving array 8; the light source 4 is disposed between the two incremental light receiving arrays 8.

[0039] In this embodiment, the light source 4 is positioned between the two incremental light-receiving arrays 8, which can illuminate the first incremental code track 6 and the second incremental code track 7 with uniform light, thereby improving the quality of the sinusoidal signal generated by the two incremental light-receiving arrays 8. This layout also promotes structural compactness and stability, enabling the entire encoder to achieve high precision and high resolution while possessing extremely high reliability and environmental adaptability.

[0040] In this embodiment, the absolute light-receiving array 5 includes strip-shaped C+ light-receiving elements 51 and C- light-receiving elements 52, which respectively receive reflected light from two absolute code tracks 3. The C- light-receiving element 52 is disposed on the side closer to the center of the circle relative to the C+ light-receiving element 51. The upper and lower edges of the C+ light-receiving element 51 are both arc-shaped.

[0041] The code disk 1 is circular, and the light emitted by the light source 4 is irradiated onto the code disk 1 in a cone shape. Therefore, the light path reflected back to the substrate 2 from the code track is also radial. The upper and lower edges of the C+ light-receiving element 51 are set as arcs, so that the shape of the C+ light-receiving element 51 matches the radial characteristics of the light path, thereby improving the uniformity of light received per unit area on the C+ light-receiving element 51.

[0042] In this embodiment, the length of the C-light-receiving element 52 along the radial direction is greater than the length of the C+light-receiving element 51.

[0043] The two absolute code tracks 3 are at different distances from the light source 4, which will cause a certain difference in the amount of light received by the two absolute light-receiving arrays 5. The C-light-receiving element 52 is farther from the light source 4, and increasing its radial length can make its light-receiving area larger, providing linear compensation for the uneven distribution of light intensity. The specific length value can be obtained from experiments or simulation software.

[0044] In this embodiment, the lower edge of the C-light-receiving element 52 is a quadratic function curve, so that the C-light-receiving element 52 and the C+light-receiving element 51 receive the same amount of light.

[0045] The quadratic function curve of the lower edge of the C-light-receiving element 52 needs to be simulated using simulation software to ensure that the lower edge contour of the C-light-receiving element 52 matches the light field. This further improves the balance of light received by the C+ light-receiving element 51 and the C-light-receiving element 52, making the intrinsic intensity of this pair of differential signal sources highly consistent. This improves the purity of the final output absolute position signal, thereby achieving high measurement accuracy and strong anti-interference capability. Furthermore, optical simulation software can be used to verify whether the light received by the C+ light-receiving element 51 and the C-light-receiving element 52 are close.

[0046] In this embodiment, each incremental light-receiving array 8 consists of several groups of incremental light-receiving elements, each group containing 4 incremental light-receiving elements, and adjacent incremental light-receiving elements are 90° out of phase for relative position counting.

[0047] In this system, the signals detected by the two incremental light-receiving elements spaced apart have a 180° phase difference. By subtracting these signals with a 180° phase difference, manufacturing errors and measurement errors within a reflective element spacing can be canceled out, resulting in two reliable signals with a 90° phase difference in electrical angle. Furthermore, using these two reliable signals, the relative position within a reflective element spacing can be determined. Using this relative position to compensate for the absolute position further improves the positioning accuracy of the absolute position.

[0048] In this embodiment, the incremental light-receiving element has a harmonic filtering profile.

[0049] The harmonic filtering profile can be a profile shape found in existing technologies, which can filter out high-order harmonics in the periodic signal generated by the incremental light-receiving element, reduce the influence of harmonics on the periodic signal, improve the accuracy of the periodic signal, and improve the utilization efficiency of the surface area of ​​the incremental light-receiving element, reduce the area of ​​the entire incremental light-receiving array 8, thereby reducing manufacturing costs.

[0050] In this embodiment, light source 4 is a monochromatic point light source.

[0051] Among them, the monochromatic point light source can produce bright and dark stripes with clearer edges, significantly improve the signal contrast between the reflective area 31 and the non-reflective area 32, and is also easier to optically design and control, which helps to achieve miniaturization and high performance of the encoder.

[0052] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural or procedural transformations made based on the content of the present utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present utility model.

Claims

1. A reflective absolute encoder, characterized in that, It includes a code disk (1), a substrate (2), and a differential processing unit; The code disk (1) is disc-shaped and has two absolute code tracks (3) arranged concentrically. Each absolute code track (3) is composed of several reflective areas (31) and non-reflective areas (32) arranged alternately. The reflective areas (31) and non-reflective areas (32) of the two absolute code tracks (3) are in opposite positions. The substrate (2) is parallel to the code disk (1), and a light source (4) and two absolute light-receiving arrays (5) are provided on the side facing the code disk (1). The two absolute light-receiving arrays (5) respectively receive the reflected light corresponding to the absolute code track (3). The differential processing unit is electrically connected to the two absolute light-receiving arrays (5) and performs differential operations on the electrical signals generated by the two absolute light-receiving arrays (5).

2. The reflective absolute encoder according to claim 1, characterized in that, It also includes a first incremental code track (6) and a second incremental code track (7) concentrically arranged on the code disk (1), and two incremental light-receiving arrays (8) correspondingly arranged on the substrate (2), the two incremental light-receiving arrays (8) respectively receiving the reflected light from the first incremental code track (6) and the second incremental code track (7).

3. The reflective absolute encoder according to claim 2, characterized in that, The first incremental code track (6) is disposed inside the second incremental code track (7), and the spacing of the reflective portion of the first incremental code track (6) is twice the spacing of the reflective portion of the second incremental code track (7).

4. The reflective absolute encoder according to claim 2, characterized in that, The absolute code channels (3) are all located inside the first incremental code channel (6) and the second incremental code channel (7), and the absolute light-receiving arrays (5) are all located inside the incremental light-receiving arrays (8); the light source (4) is located between the two incremental light-receiving arrays (8).

5. The reflective absolute encoder according to claim 4, characterized in that, The absolute light-receiving array (5) includes strip-shaped C+ light-receiving elements (51) and C- light-receiving elements (52), which respectively receive the reflected light from the two absolute code tracks (3). The C- light-receiving element (52) is disposed on the side closer to the center of the circle relative to the C+ light-receiving element (51). The upper and lower edges of the C+ light-receiving element (51) are both arc-shaped.

6. The reflective absolute encoder according to claim 5, characterized in that, The length of the C-light-receiving element (52) along the radial direction is greater than the length of the C+light-receiving element (51).

7. The reflective absolute encoder according to claim 6, characterized in that, The lower edge of the C-light-receiving element (52) is a quadratic function curve, so that the C-light-receiving element (52) receives the same amount of light as the C+light-receiving element (51).

8. The reflective absolute encoder according to claim 2, characterized in that, Each of the incremental light-receiving arrays (8) consists of several groups of incremental light-receiving elements, each group containing 4 incremental light-receiving elements, and adjacent incremental light-receiving elements are 90° out of phase for relative position counting.

9. The reflective absolute encoder according to claim 8, characterized in that, The incremental light-receiving element has a harmonic filtering profile.

10. The reflective absolute encoder according to claim 1, characterized in that, The light source (4) is a monochromatic point light source.

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