High-precision absolute position detection photoelectric encoder system
By integrating incremental and reference code tracks into the photoelectric encoder system and using a signal processing module to process the periodic and differentiated signals of the photoelectric encoder, the structural complexity and accuracy limitations of existing photoelectric encoders in full-stroke absolute position detection are solved, achieving high-precision and low-cost absolute position detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-04-03
AI Technical Summary
Existing photoelectric encoder systems are complex in structure and costly when full-stroke absolute position detection is required, and cannot achieve high-precision absolute position recognition. In particular, incremental encoders cannot provide full-stroke absolute position information, and absolute encoders have problems such as complex code track design and high risk of signal interference.
The photoelectric encoder system, which integrates incremental and reference code tracks, modulates the light beam emitted by the light source onto the code disk. The incremental and reference code detectors output periodic and differentiated signals respectively, which are then processed by the signal processing module to achieve high-precision absolute position detection.
It achieves high-precision full-stroke absolute position detection with a simple structure and easy integration, reducing system cost and improving the accuracy and reliability of position detection.
Smart Images
Figure CN121783214A_ABST
Abstract
Description
(I) Technical Field
[0001] This invention relates to a high-precision absolute position detection photoelectric encoder system, which can be used in industrial automation, robotics, precision instruments, motor control and other fields that require real-time acquisition of absolute position information and high-resolution positioning, and belongs to the field of photoelectric detection technology. (II) Background Technology
[0002] As a high-precision position detection device, photoelectric encoders are widely used in industrial automation, CNC machine tools, robots, aerospace and other fields. Their core function is to convert mechanical displacement into electrical signals and output position information.
[0003] Existing photoelectric encoders are mainly divided into two categories: incremental encoders and absolute encoders. Incremental encoders achieve displacement measurement by outputting periodic incremental signals. They have advantages such as simple structure, fast response, and high resolution. However, they cannot directly obtain absolute position information and need to be recalibrated after power failure, which limits their application in scenarios requiring continuous position tracking.
[0004] Absolute encoders, through their unique code disk patterns, can output corresponding absolute position information at any position without needing to be zeroed. However, traditional absolute encoders have complex code track designs, often using Gray code, binary code, and other patterns. This results in problems such as a large number of code tracks, difficulty in engraving, and limited accuracy improvement. Furthermore, their physical accuracy and resolution are often limited, leading to a significant increase in system cost.
[0005] In the existing technology, some solutions attempt to combine the advantages of incremental and absolute encoders by adding a reference zero-position signal to achieve absolute position detection. However, the reference zero-position signal can only provide a single reference position and cannot achieve absolute position recognition across the entire stroke range. Other solutions adopt a multi-track combination design, but suffer from drawbacks such as structural redundancy, high risk of signal interference, and difficulty in debugging.
[0006] Therefore, there is an urgent need for a photoelectric encoder system that is simple in structure, easy to integrate, and capable of high-precision full-stroke absolute position detection. (III) Summary of the Invention
[0007] The purpose of this invention is to provide a high-precision absolute position detection photoelectric encoder system, which consists of a light source (1), a code disk (2), an encoder chip (3), and a signal processing module (4). The code disk (2) is provided with an incremental code track (200) and a reference code track (210); the encoder chip (3) integrates an incremental code detector (300) and a reference code detector (310).
[0008] The objective of this invention is achieved through the following technical solution: the light beam emitted by the light source (1) is modulated by the code disk (2) and then received and detected by the incremental code detector (300) and the reference code detector (310) on the encoder chip (3); wherein, the incremental code channel (200) periodically modulates the light beam, so that the incremental code detector (300) outputs a periodic incremental signal (301); the reference code channel (210) performs position differential modulation on the light beam, so that the reference code detector (310) outputs a reference signal (311) with a width difference; the incremental signal (301) and the reference signal (311) are processed by the signal processing module (4), thereby enabling accurate acquisition of absolute position information.
[0009] The light source (1) is one or more of the following: collimated light source, divergent light source, point light source, surface light source, volume light source, or multicolor light source or combination thereof.
[0010] The code disk (2) integrates an incremental code track (200) and a reference code track (210); wherein the incremental code track (200) is periodically distributed, and the reference code track (210) has differences at different positions. After being modulated by the light source (1), light spots of different widths are formed on the reference code detector (310), so that each position of the code disk (2) corresponds to unique encoded information.
[0011] The encoder chip (3) includes at least one incremental code detector (300) that is matched with the incremental code track (200), and the resulting incremental signal (301) is periodically distributed.
[0012] The encoder chip (3) includes at least one reference code detector (310) that matches the light spot modulated by the reference code track (210).
[0013] The reference signals (311) generated by the reference code detector (310) are different, and the width of each reference signal (311) corresponds one-to-one with the width of the light spot.
[0014] The signal processing module (4) acquires and processes the incremental signal (301) and the reference signal (311). By subdividing the incremental signal (301), high-precision displacement information is obtained. At the same time, by identifying the width of the reference signal (311), its corresponding absolute position information is determined. Finally, by combining the subdivided high-precision displacement information with the determined absolute position information, the accurate absolute position is obtained.
[0015] The width recognition method of the signal processing module (4) includes, but is not limited to, recognizing the number of cycles of the incremental signal (301), the number of pulses of the sine and cosine signals, and the angle range of the incremental phase contained in the reference signal (311) of different widths, and outputting the corresponding absolute code position by querying the pre-stored mapping relationship table.
[0016] The width recognition method of the signal processing module (4) includes, but is not limited to, using an incremental signal (301) with a fixed width as a reference to identify the threshold width or edge time of the reference signal (311), thereby determining its precise position information. (iv) Description of the attached drawings
[0017] Figure 1 This is a schematic diagram of a high-precision absolute position detection photoelectric encoder system. In the diagram, the light beam emitted by the light source (1) is modulated by the code disk (2) and then received and detected by the incremental code detector (300) and the reference code detector (310) on the encoder chip (3), respectively. The incremental code track (200) periodically modulates the light beam, causing the incremental code detector (300) to output a periodic incremental signal (301). The reference code track (210) performs position-differentiated modulation on the light beam, causing the reference code detector (310) to output a reference signal (311) with a different width. After the incremental signal (301) and the reference signal (311) are processed by the signal processing module (4), the absolute position information can be accurately obtained.
[0018] Figure 2 This is a schematic diagram of the absolute code signal processing flow of the signal processing module. After the code disk (2) modulates the emitted beam, it generates an incremental signal (301) and a reference signal (311). First, the incremental signal is subdivided and direction-identified to obtain a high-resolution relative displacement. Then, by identifying the number of incremental signal cycles during the high level of the reference signal (311), a coarse absolute position value is calculated. Finally, the coarse absolute position value and the relative displacement are fused and calculated to output a precise absolute position value.
[0019] Figure 3This is a schematic diagram of a transmission-type high-precision absolute position detection grating ruler system. The light source (1) is an infrared LED point light source, which emits light that illuminates the grating ruler (2). The surface of the grating ruler (2) is engraved with incremental code tracks (200) and reference code tracks (210), which are arranged parallel to each other along the length of the grating ruler. Specifically, the incremental code track (200) is composed of periodically arranged bright and dark lines with equal spacing and width; the reference code track (210) is designed as a light-transmitting window with a width that varies according to a specific rule, ensuring that the window width corresponding to any straight line position is unique, thereby achieving coarse positioning of the absolute position. The grating ruler chip (3) integrates a photodiode array as a detection unit, one of which is an incremental code detector (300) used to receive the periodic incremental light signal modulated by the incremental code track (200) and convert it into an incremental electrical signal (301); the other is a reference code detector (310) used to receive the reference light signal transmitted through the reference code track (210). When the grating ruler (2) moves relative to the grating ruler chip (3), the reference code detector (310) outputs a reference electrical signal (311) whose pulse width corresponds one-to-one with the physical width of the light-transmitting window. The signal processing module (4) synchronously acquires the incremental electrical signal (301) and the reference electrical signal (311), and after preprocessing, subdivides and performs direction discrimination processing on the incremental signal to obtain a high-resolution relative displacement. At the same time, by identifying the number of incremental signal cycles during the high level of the reference signal (311), a coarse absolute position value is calculated to determine the large position range. Finally, the coarse absolute position value and the relative displacement value are fused and calculated to output a precise absolute position value.
[0020] Figure 4This is a schematic diagram of a reflective high-precision absolute position detection photoelectric encoder system. The light source (1) adopts an infrared LED point light source, and the light emitted by it illuminates the code disk (2). The code disk (2) is a glass code disk with concentric ring-shaped incremental code tracks (200) and reference code tracks (210) engraved on its surface. The incremental code track (200) is composed of periodically arranged bright and dark lines with equal spacing and width. The reference code track (210) is designed as a series of light-transmitting windows (or reflective strips) with widths varying according to a specific rule, ensuring that the window width corresponding to each angle position is unique. The encoder chip (3) integrates a photodiode array as a detector. One set serves as an incremental code detector (300) to receive the incremental signal (301) with periodic brightness and darkness changes modulated by the incremental code track (200). The other set serves as a reference code detector (310) to receive the electrical signal transmitted through the reference code track (210). When the code disk rotates, the reference window sweeps across the detector, and the reference code detector (310) outputs a reference signal (311) with a pulse width that corresponds one-to-one with the physical width of the current window. The signal processing module (4) is an external microprocessor. It first preprocesses the acquired reference signal to remove interference, then times the rising and falling edges of the reference signal to obtain the actual width of the reference signal, and finally combines the subdivision processing results of the incremental signal to obtain the accurate absolute position. (V) Detailed Implementation Example 1: As Figure 3As shown, this embodiment provides a transmissive high-precision absolute position detection grating ruler system, including a light source (1), a grating ruler (2), a grating ruler chip (3), and a signal processing module (4). The components work together to achieve high-precision absolute position detection in a straight line direction. The specific structure and working principle are as follows: The light source (1) uses an infrared LED point light source, whose emitted light illuminates the grating ruler (2). The surface of the grating ruler (2) is engraved with incremental code tracks (200) and reference code tracks (210), which are arranged parallel to each other along the length of the grating ruler. Specifically, the incremental code track (200) is formed by periodically arranging bright and dark lines of equal spacing and width; the reference code track (210) is designed as a light-transmitting window with a width varying according to a specific rule, ensuring that the window width corresponding to any straight line position is unique, thus achieving coarse positioning of the absolute position. The grating ruler chip (3) integrates a photodiode array as a detection unit. One set is an incremental code detector (300), which is used to receive the periodic incremental optical signal modulated by the incremental code channel (200) and convert it into an incremental electrical signal (301). The other set is a reference code detector (310), which is used to receive the reference optical signal transmitted through the reference code channel (210). When the grating ruler (2) moves relative to the grating ruler chip (3), the reference code detector (310) outputs a reference electrical signal (311) whose pulse width corresponds one-to-one with the physical width of the light transmission window. The signal processing module (4) synchronously acquires the incremental electrical signal (301) and the reference electrical signal (311). After preprocessing, the incremental signal is subdivided and direction-identified to obtain a high-resolution relative displacement. At the same time, by identifying the number of incremental signal cycles during the high level of the reference signal (311), the coarse value of the absolute position is calculated. Finally, the coarse value of the absolute position and the relative displacement are fused and calculated to output the accurate absolute position value. Example 2: Figure 4As shown, this embodiment provides a reflective high-precision absolute position detection photoelectric encoder system, including a light source (1), a code disk (2), an encoder chip (3), and a signal processing module (4); wherein the light source (1) adopts an infrared LED point light source, the light emitted by it illuminates the code disk (2), the code disk (2) is a glass code disk, the surface of which is engraved with concentric ring-shaped incremental code tracks (200) and reference code tracks (210), the incremental code tracks (200) are periodically arranged by light and dark engraving lines with equal spacing and equal width, and the reference code tracks (210) are designed as a series of light-transmitting windows (or reflective strips) with widths varying according to a specific rule to ensure that the window width corresponding to each angular position is unique; the encoder chip (3) integrates a photodiode array as a detector on its surface, one of which serves as an incremental code The detector (300) is used to receive the incremental light signal with periodic brightness changes modulated by the incremental code channel (200) and convert it into an incremental electrical signal (301); another set serves as a reference code detector (310) to receive the reference light signal transmitted through the reference code channel (210) and convert it into a reference electrical signal (311); when the code disk rotates, the reference window sweeps across the detector, and the reference code detector (310) will output a reference signal (311) whose pulse width corresponds one-to-one with the physical width of the current window; the signal processing module (4) is an external microprocessor, which first preprocesses the acquired reference signal to remove interference, then times the rising and falling edges of the reference signal to obtain the actual width of the reference signal, and finally combines the subdivision processing results of the incremental signal to obtain the precise absolute position.
Claims
1. A high-precision absolute position detection photoelectric encoder system. Its features are: The system consists of a light source (1), a code disk (2), an encoder chip (3), and a signal processing module (4). The code disk (2) is provided with an incremental code track (200) and a reference code track (210); the encoder chip (3) integrates an incremental code detector (300) corresponding to the incremental code track (200) and a reference code detector (310) corresponding to the reference code track (210); the light beam emitted by the light source (1) in the system is modulated by the code disk (2) and then received and detected by the incremental code detector (300) and the reference code detector (310) on the encoder chip (3); the incremental code track (200) periodically modulates the light beam, so that the incremental code detector (300) outputs a periodic incremental signal (301); the reference code track (210) modulates the light beam with positional differences, so that the reference code detector (310) outputs a reference signal (311) with different widths; finally, the incremental signal (301) and the reference signal (311) are processed by the signal processing module (4) to obtain the absolute position information.
2. The high-precision absolute position detection photoelectric encoder system according to claim 1, characterized in that: The light source (1) is one or more of the following: collimated light source, divergent light source, point light source, surface light source, and volume light source. It can also be a multi-color light source or a polychromatic light source and its combination.
3. The high-precision absolute position detection photoelectric encoder system according to claim 1, characterized in that: The code disk (2) is provided with an incremental code track (200) and a reference code track (210); wherein, the incremental code track (200) is periodically distributed, while the reference code track (210) has differences at different positions, and after being modulated by the light source (1), it forms light spots of different widths, so that the encoding information corresponding to each position is unique.
4. The high-precision absolute position detection photoelectric encoder system according to claim 1, characterized in that: The encoder chip (3) includes at least one incremental code detector (300), wherein the incremental code detector (300) is matched with the incremental code track (200), and the generated incremental signal (301) is periodically distributed.
5. The high-precision absolute position detection photoelectric encoder system according to claim 1, characterized in that: The encoder chip (3) includes at least one reference code detector (310), wherein the reference code detector (310) is matched with the light spot modulated by the reference code track (210).
6. The high-precision absolute position detection photoelectric encoder system according to claim 5, characterized in that: The reference signals (311) generated by the reference code detector (310) are different, and the width of each reference signal (311) corresponds one-to-one with the width of the light spot.
7. The high-precision absolute position detection photoelectric encoder system according to claim 1, characterized in that: The signal processing module (4) acquires and processes the incremental signal (301) and the reference signal (311). By subdividing the incremental signal (301), precise displacement information is obtained. At the same time, the position information of the reference signal (311) is determined by identifying its width. Finally, the precise absolute position is obtained by combining the displacement information and the position information.
8. The high-precision absolute position detection photoelectric encoder system according to claim 7, characterized in that: The width recognition method of the signal processing module (4) includes, but is not limited to, recognizing the number of cycles of the incremental signal (301), the number of pulses of the sine and cosine signals, and the angle range of the incremental phase contained in the reference signal (311) of different widths, and outputting the absolute code position after querying the corresponding mapping relationship.
9. The high-precision absolute position detection photoelectric encoder system according to claim 7, characterized in that: The width recognition method of the signal processing module (4) includes, but is not limited to, using an incremental signal (301) of fixed width to identify the threshold of the reference signal (311) to determine its precise position information.