A dual-system absolute encoder device and its usage method

Abstract

This invention relates to a dual-system absolute encoder device and its usage method. The device includes a PCB board, a magnet, a magnetic induction chip, a reflective induction chip, an incremental reflective code disk, an encoder bracket, and a code disk holder. The PCB board is placed on the encoder bracket. The magnet is embedded in the center of the concentric circle containing the incremental reflective code disk. The magnetic induction chip is located on the PCB board and is inductively connected to the magnet, forming a magnetic single-turn absolute encoder. The incremental reflective code disk is placed on the code disk holder. The reflective induction chip is located on the PCB board, wherein the reflective induction chip corresponds to the code track of the incremental reflective code disk, forming an incremental reflective encoder. The magnet and the incremental reflective code disk form a combined code disk, which, together with the magnetic induction chip and the reflective induction chip, realizes the dual-system combination of a magnetic single-turn absolute encoder and an incremental reflective encoder. Compared with the prior art, this invention has the advantages of small size, high reliability and safety, and high accuracy.

Description

Technical Field

[0001] This invention relates to the field of encoders, and in particular to a dual-system absolute encoder device and its method of use. Background Technology

[0002] Currently, there are three main types of photoelectric absolute encoders: 1) Binary photocell: Directly reads the absolute position of a single turn upon power-up. Disadvantages: Higher cost, susceptible to axial movement and oil vapor; 2) Vernier photocell: Lower cost. Disadvantages: Susceptible to axial movement and oil vapor. The absolute position of a single turn is read by vernier calculation upon power-up. If the position changes slightly, the vernier calculation is prone to errors; 3) M-sequence photocell: Directly reads the absolute position of a single turn upon power-up. Disadvantages: Higher cost, less sensitive to axial movement and oil vapor than binary and vernier schemes, but axial movement must still be kept within 0.5mm.

[0003] A search revealed Chinese patent publications CN110345976A and CN 210014791U, both mentioning composite encoder patents combining a magnetic single-turn absolute encoder and a photoelectric encoder. These patents combine several high-resolution encoders, one using a magnetic encoder to extract high-bit data and the other using a photoelectric encoder to extract low-bit data. However, such encoders suffer from significant positioning accuracy deviations if there are discrepancies in the high- and low-bit combination. Furthermore, this type of encoder requires two magnetic induction chips, resulting in higher costs. Additionally, it cannot promptly diagnose encoder malfunctions. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art by providing a high-precision, safe, reliable, and inexpensive dual-system absolute encoder device and its usage method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] According to one aspect of the present invention, a dual-system absolute encoder device is provided, comprising a PCB board, a magnet, a magnetic induction chip, a reflective induction chip, an incremental reflective code disk, an encoder bracket, and a code disk holder; the PCB board is placed on the encoder bracket; the magnet is embedded in the center of the concentric circle of the incremental reflective code disk; the magnetic induction chip is located on the PCB board and is inductively connected to the magnet, forming a magnetic single-turn absolute encoder; the incremental reflective code disk is placed on the code disk holder; the reflective induction chip is located on the PCB board, wherein the reflective induction chip corresponds to the code track of the incremental reflective code disk, forming an incremental reflective encoder;

[0007] The magnet and the incremental reflective code disk form a combined code disk, which, together with the magnetic induction chip and the reflective induction chip, realizes the dual-system combination of the magnetic single-turn absolute encoder and the incremental reflective encoder.

[0008] As a preferred technical solution, the magnet is cylindrical or ring-shaped.

[0009] As a preferred technical solution, the number of magnetic induction chips is only one.

[0010] As a preferred technical solution, the magnetic induction chip is a magnetic induction chip made based on AMR, TMR or GMR technology.

[0011] As a preferred technical solution, the incremental reflective code disk can be replaced with an incremental transmissive code disk.

[0012] As a preferred technical solution, the optical coding track in the incremental reflective code disk is a sine / cosine incremental code track, and has a zero-bit signal.

[0013] As a preferred technical solution, the incremental reflective encoder outputs a digital Z signal per revolution.

[0014] According to another aspect of the present invention, a method of using the dual-system absolute encoder device is provided, the method employing a magnetoelectric absolute signal plus a photoelectric incremental signal, obtaining a magnetoelectric absolute position signal through a single-turn magnetic absolute encoder and obtaining a high-precision photoelectric incremental signal through an incremental reflective encoder; the magnetoelectric absolute signal and the photoelectric incremental signal are used interchangeably.

[0015] As a preferred technical solution, the signal switching includes the following steps:

[0016] Step 1: After the initial power-on initialization, the MCU reads the single-turn absolute position information of the magnetic encoder and determines the absolute angle of the encoder when it is powered on by the high-resolution absolute value characteristics of the magnetic single-turn absolute encoder itself.

[0017] Step 2: When the encoder detects the Z signal of the incremental reflective encoder after running one revolution, the encoder is converted from the original magnetic single-turn absolute encoder to a high-resolution incremental reflective encoder.

[0018] Step 3: If the incremental signal of the incremental reflective encoder becomes abnormal during operation, the encoder will be converted back into a magnetic single-turn absolute encoder.

[0019] As a preferred technical solution, this method enables mutual correction and supplementation of signals from the two systems.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1) Small size

[0022] Because of the use of an incremental reflective encoder with a single-turn absolute encoder, the axial spacing between the chip and the code disk can be reduced to the millimeter level. Generally, photoelectric encoders require this distance to be within 0.5mm. This greatly reduces the size requirements of the mechanical structure during installation, which is beneficial for mass production and installation.

[0023] 2) The dual encoder system has complementary functions.

[0024] The proposed solution is actually two complementary encoder systems. It solves the problem of low accuracy of magnetic absolute encoders in high-temperature environments, and also addresses the limitation of incremental reflective encoders in failing to recognize the current position upon power-up, thus realizing the function of a dual-system encoder.

[0025] 3) High accuracy

[0026] That is, the dual-system absolute encoder of the present invention is a combination of two complete high-resolution encoders, each of which can achieve high-resolution counting independently. Moreover, during the first calibration, this encoder can use the high accuracy of the incremental reflective encoder to compensate for the accuracy of the magnetic single-turn absolute encoder, thereby improving the position accuracy of the magnetic single-turn absolute encoder when it is powered on.

[0027] 4) Low cost

[0028] The solution proposed in this invention has an advantage in material cost compared to traditional absolute encoders. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the dual-system absolute encoder.

[0030] Figure 2 This is a schematic diagram of a combination encoder.

[0031] Figure 3 This is a schematic diagram of an incremental reflective encoder.

[0032] Figure 4 This is a graph showing the output signal of an incremental reflective encoder.

[0033] Figure 5 This is a schematic diagram of a magnetic encoder in operation.

[0034] Figure 6 This is a flowchart of the workflow for a dual-system absolute encoder. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] Example

[0037] like Figure 1 As shown, a dual-system absolute encoder device includes a PCB board 1, a magnet 2, a magnetic induction chip 3, a reflective induction chip 4, an incremental reflective code disk 5, an encoder bracket 6, and a code disk holder 7. The PCB board 1 is placed on the encoder bracket 6 with the component side facing down. The magnet 2 is embedded in the center of the incremental reflective code disk 5. The magnetic induction chip 3 is located on the PCB board 1 and is coaxially mounted with the magnet 2. The incremental reflective code disk 5 is placed on the code disk holder 7. The reflective induction chip 4 is located on the PCB board 1, wherein the reflective induction chip 4 is opposite to the outer ring of the incremental reflective code disk 5.

[0038] The present invention relates to a dual-system absolute encoder device, comprising a magnetic single-turn absolute encoder and an incremental reflective encoder. The two encoders can be switched and used interchangeably and complement each other, which not only solves the problems of accuracy deviation and large speed fluctuation of magnetic encoders, but also solves the shortcomings of incremental reflective photoelectric encoders that cannot obtain absolute position information of the encoder upon power-up, thus realizing a dual-system encoder.

[0039] like Figure 2 As shown, the combined code disk consisting of magnet 2 and incremental reflective code disk 5 has a magnet in the center, which provides a pair of N and S magnetic fields to ensure that the magnetic single-turn absolute encoder has a stable magnetic field; the outside consists of two reflective encoder code disks, which provide SIN, COS analog signals and digital Z signals to the incremental code disk of the reflective encoder.

[0040] like Figure 3 and 4 The diagram shows the operation of an incremental reflective encoder. During normal operation, the incremental reflective encoder chip outputs SIN and COS signals. By applying a subdivision algorithm to the analog signal, the resolution of the incremental encoder is greatly improved. The incremental reflective encoder outputs one Z signal per revolution. After the encoder is powered on and detects the Z signal for the first time, it switches from a single-turn magnetic encoder to a high-resolution incremental reflective encoder. Subsequent operation uses the incremental reflective encoder for counting and positioning.

[0041] like Figure 5The schematic diagram of the magnetic encoder shows that when the encoder is powered on, the magnetic sensor chip outputs SIN and COS signals. The current absolute position information of the encoder is obtained through subdivision technology or directly read through the communication protocol built into the magnetic sensor itself. Due to the inherent characteristics of magnetic encoders, when a single-turn magnetic encoder outputs high resolution (above 20 bits), the low-level pulse output fluctuates significantly in the encoder's disabled state. In this case, the low-level fluctuation of the incremental reflective photoelectric encoder can compensate for the low-level fluctuation of the single-turn absolute encoder, thus ensuring a stable signal output during the initial power-on phase.

[0042] like Figure 6 The diagram shows the operation of a dual-system absolute encoder. After power-on, the encoder initializes, and the MCU reads the single-turn absolute position information of the magnetic encoder. The MCU determines the absolute angle of the encoder upon power-on based on the high-resolution absolute characteristics of the magnetic encoder itself. When the encoder detects the Z-signal from the incremental reflective encoder after one revolution, it switches from a single-turn magnetic absolute encoder to an incremental high-resolution encoder. If the incremental reflective encoder's code disk becomes abnormal due to external contamination or other abnormalities during operation, the encoder can revert to a single-turn magnetic absolute encoder. This switching mechanism primarily addresses the issues of accuracy deviation and large speed fluctuations in magnetic encoders, and also overcomes the limitation of incremental reflective photoelectric encoders in failing to acquire absolute position information upon power-on, thus realizing a dual-system encoder.

[0043] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A dual-system absolute encoder device, characterized in that, The encoder includes a PCB board (1), a magnet (2), a magnetic induction chip (3), a reflective induction chip (4), an incremental reflective code disk (5), an encoder bracket (6), and a code disk holder (7). The PCB board (1) is placed on the encoder bracket (6). The magnet (2) is embedded in the center of the concentric circle where the incremental reflective code disk (5) is located. The magnetic induction chip (3) is located on the PCB board (1) and is inductively set with the magnet (2) to form a magnetic single-turn absolute encoder. The incremental reflective code disk (5) is placed on the code disk holder (7). The reflective induction chip (4) is located on the PCB board (1), wherein the reflective induction chip (4) corresponds to the code track of the incremental reflective code disk (5) to form an incremental reflective encoder. The magnet (2) and the incremental reflective code disk (5) form a combined code disk, which together with the magnetic induction chip (3) and the reflective induction chip (4) realizes the dual-system combination of the magnetic single-turn absolute encoder and the incremental reflective encoder. The device achieves mutual correction and supplementation of signals from two systems. When powered on, the encoder device uses the high precision of the incremental reflective encoder to compensate for the precision of the magnetic single-turn absolute encoder. The low-position fluctuation of the incremental reflective photoelectric encoder compensates for the low-position fluctuation of the magnetic single-turn absolute encoder, so that the encoder maintains a stable signal output in the initial stage of power-on.

2. The dual-system absolute encoder device according to claim 1, characterized in that, The magnet (2) is cylindrical or ring-shaped.

3. The dual-system absolute encoder device according to claim 1, characterized in that, The number of magnetic induction chips (3) is only 1.

4. The dual-system absolute encoder device according to claim 1, characterized in that, The magnetic induction chip (3) is a magnetic induction chip made based on AMR, TMR or GMR technology.

5. The dual-system absolute encoder device according to claim 1, characterized in that, The incremental reflective code disk (5) can be replaced with an incremental transmissive code disk.

6. The dual-system absolute encoder device according to claim 1, characterized in that, The optical coding track in the incremental reflective code disk (5) is a sine-cosine incremental code track, and has a zero-bit signal.

7. The dual-system absolute encoder device according to claim 1, characterized in that, The incremental reflective encoder (5) outputs a zero-position signal per revolution.

8. A method of using the dual-system absolute encoder device of claim 1, characterized in that, This method employs a combination of magnetoelectric absolute signal and photoelectric incremental signal. The magnetoelectric absolute position signal is obtained through a single-turn magnetic absolute encoder, and the high-precision photoelectric incremental signal is obtained through an incremental reflective encoder. The magnetoelectric absolute signal and the photoelectric incremental signal are used interchangeably.

9. The method of use according to claim 8, characterized in that, The signal switching includes the following steps: Step 1: After the initial power-on initialization, the MCU reads the single-turn absolute position information of the magnetic encoder and determines the absolute angle of the encoder when it is powered on by the high-resolution absolute value characteristics of the magnetic single-turn absolute encoder itself. Step 2: When the encoder detects the Z signal of the incremental reflective encoder after running one revolution, the encoder is converted from the original magnetic single-turn absolute encoder to a high-resolution incremental reflective encoder. Step 3: If the incremental signal of the incremental reflective encoder becomes abnormal during operation, the encoder will be converted back into a magnetic single-turn absolute encoder.

10. The method of use according to claim 8, characterized in that, This method enables mutual correction and supplementation of signals between the two systems.

Images