Vernier type grating coded disc, image type photoelectric encoder and position reading method

Abstract

The invention provides a vernier type grating code disc, an image type photoelectric encoder and a position reading method.The vernier type grating code disc comprises a grating code disc, the grating code disc is in a disc shape, and the periphery of the grating code disc is coaxially and sequentially provided with a main code channel, a vernier code channel, a segment code channel and a circle code channel from outside to inside; the scribed line number of each code channel and the data length meet the following relation: M = 2UBLS + UBLN; n is equal to 2UBLS + UBLN-1; s is equal to 2UBLS + UBLN <-2 > UBLN; z = 1; the scribed line of the circle code channel and one of the scribed lines of the segment code channel, the vernier code channel and the main code channel are all located on the same radius line of the grating code disc, and the scribed lines of the segment code channel, the vernier code channel, the main code channel and the circle code channel located on the same radius line of the grating code disc are initial scribed lines. By changing the coded disc structure and the coding mode, the absolute position of the image type photoelectric encoder is read, and the resolution is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of encoders, and in particular to a vernier grating code disk, an image-type photoelectric encoder and a position reading method. Background Art

[0002] Photoelectric encoders are sensors that convert mechanical angular displacement (angle or length) into electrical signals. They are widely used in industrial fields such as CNC machine tools and robots to obtain position and speed information.

[0003] There are two types of photoelectric encoders: incremental and absolute. The incremental encoder has a simple structure and can provide relative position, but it needs to provide a zero point for reference positioning, that is, the operation of finding the reference point signal must be performed after power-on before the absolute position coordinates can be established. Compared with the incremental encoder, the position of the absolute encoder is uniquely determined, and there is no need to memorize and find the reference point operation. It can provide absolute position information at the initial power-on.

[0004] Traditional absolute encoders use binary or Gray code encoding. If you want to improve its resolution, you need to increase the number of physical lines on the grating code disk. When the position information resolution requirement is high, the code disk is complicated to manufacture and the position calculation process is complicated.

[0005] Therefore, it is necessary to provide a vernier grating code disk, an image-type photoelectric encoder and a position reading method to effectively solve the above problems. Summary of the invention

[0006] The present invention provides a vernier grating code disk, an image type photoelectric encoder and a position reading method. By changing the code disk structure and the encoding method, the absolute position reading of the image type photoelectric encoder is realized and the resolution is improved.

[0007] The embodiment of the present invention provides a vernier grating code disk, including a grating code disk, the grating code disk is in the shape of a disk, and the grating code disk is coaxially arranged with a main code track, a vernier code track, a segment code track and a circle code track in sequence from the outside to the inside on the outer periphery, and the number of engraved lines and the data length of each code track satisfy the following relationship:

[0008] M=2 UBL_S+UBL_N

[0009] N=2 UBL_S+UBL_N -1

[0010] S=2 UBL_S+UBL_N -2 UBL_N

[0011] Z=1

[0012] Wherein, M is the number of lines of the main code channel, N is the number of lines of the vernier code channel, S is the number of lines of the segment code channel, Z is the number of lines of the circle code channel, UBL_N is the data bit length obtained according to the phase difference between the vernier code channel and the main code channel, and UBL_S is the data bit length obtained according to the phase difference between the segment code channel and the main code channel;

[0013] The engraved lines of the circle digital track and one of the engraved lines of the segment code track, the vernier code track and the main code track are all located on the same radius line of the grating code disk. The engraved lines of the segment code track, the vernier code track and the main code track and the engraved lines of the circle digital track located on the same radius line of the grating code disk are initial engraved lines.

[0014] Preferably, the number of lines of the main code track, the vernier code track and the segment code track of the grating code disk is set according to the accuracy requirement of the grating code disk. The accuracy of the grating code disk is 2 n , then the number of lines on the main code channel is 2 n , that is, UBL_S+UBL_N=n; the number of lines of the main code channel / cursor code channel / segment code channel is one of the following arrays: 16 / 15 / 12, 32 / 31 / 28, 64 / 63 / 56, 128 / 127 / 120, 256 / 255 / 240, 512 / 511 / 496, 1024 / 1023 / 992, 2048 / 2047 / 2016.

[0015] Based on the same concept, the present invention also provides an image-type photoelectric encoder, comprising the above-mentioned vernier grating code disk, a light source, a rotating shaft, an image sensor and a signal processing module, wherein the rotating shaft is vertically fixed to the center of the grating code disk, the light source is arranged on one side of the grating code disk and makes the light of the light source opposite to the engraved lines of the code path of the grating code disk, the image sensor is arranged on the other side of the grating code disk, and the image sensor obtains an image formed by the light of the light source passing through the engraved lines of the grating code disk when the grating code disk rotates, and the signal processing module is connected to the image sensor to obtain image data, processes the image data and calculates the rotation speed and angle information.

[0016] Preferably, the signal processing module includes a control circuit, an image processing circuit, a memory, a time-to-digital converter and a data output interface; the control circuit is connected to the image sensor, the image processing circuit, the memory and the time-to-digital converter, and the image processing circuit is connected to the control circuit, the memory and the data output interface; the control circuit sends the image data and the time data calculated by the time-to-digital converter to the memory, and the image processing circuit acquires the image data, performs image recognition through an image recognition algorithm and calculates the rotation speed and angle information in combination with the time data.

[0017] Preferably, the pixel size of the image sensor needs to satisfy the following formula:

[0018]

[0019] Wherein, D is the side length of the pixel of the image sensor, θ0 is the minimum angle difference between the lines of the main code track, the vernier code track and the segment code track except the initial code track, and R is the radius of the grating code disk.

[0020] Based on the same concept, the present invention also provides a position reading method of the above-mentioned image type photoelectric encoder, wherein the number of times the engraved lines of the circle digital track of the grating code disk pass through the image sensor is used as the number of full circles of rotation of the grating code disk; the angle subdivision value of the main code track and the vernier code track of the grating code disk is used as the coarse code for angle calibration, the angle subdivision value of the main code track and the segment code track is used as the sub-fine code for angle calibration, the signal angle value corresponding to the main code track is used as the fine code for angle calibration, and the coarse code, sub-fine code and fine code are spliced ​​to obtain the angle rotated by the current position relative to the zero point, including the following steps:

[0021] Counting the number of times that the engraved lines of the circle digital track of the grating code disk pass through the image sensor to obtain the number of full circles of the grating code disk;

[0022] Calculate the angle of the current position relative to the zero point. The zero point is the position of the initial scale line. It is calculated by the following formula:

[0023] θ=(θ M -θ N )K MN +(θ M -θ S )K MS +θ M

[0024] Among them, θ is the angle of the current position relative to the zero point, θ M ,θ N ,θ S They are the phase angles corresponding to the main code channel, cursor code channel and segment code channel in the current single signal cycle;

[0025] K MN and K MS They are different combinations of the number of whole signal cycles that the main code channel and the cursor code channel, and the main code channel and the segment code channel have rotated relative to the zero point.

[0026] Preferably, the numbers of lines of the main code channel, the vernier code channel and the segment code channel are M, N and S respectively.

[0027] K MN Satisfies the following formula:

[0028] K MN =K M or K MN =KN

[0029] Among them, K M , K N Indicates the number of whole signal cycles that the main code channel and the cursor code channel have rotated relative to the zero point at the current position;

[0030] K MS Satisfies the following formula:

[0031] K MS =K S ,K S +1,...K M

[0032] Among them, K M , K S Indicates the number of whole signal cycles that the main code channel and segment code channel have rotated relative to the zero point at the current position.

[0033] Preferably, the method further includes calculating the phase angle θ corresponding to the main code channel, the cursor code channel, and the segment code channel in the current single signal cycle by the centroid method. M ,θ N ,θ S .

[0034] Preferably, the method further includes calculating the rotation speed of the grating code disk and counting the number of whole signal cycles of the main code channel within the time T. The rotation speed of the grating code disk is calculated by the following formula:

[0035]

[0036] Among them, ω is the rotation speed of the grating code disk; B is the number of whole signal cycles of the main code channel within the time T, and M is the number of lines of the main code channel.

[0037] Preferably, the method further comprises the following step: confirming whether the engraved lines of the circle digital track of the grating code disk pass through the image sensor by scanning the grayscale value change on a certain column or the grayscale value change on a suitable row of the image sensor.

[0038] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0039] The embodiments of the present invention provide a vernier grating code disk, an image-type photoelectric encoder, and a position reading method. The vernier grating code disk applies the vernier principle to the grating code disk. Compared with the combination of multiple coarse code channels and one subdivided code channel, the code channel is more concise and the size of the code disk can be smaller. The design of the main code channel, the vernier code channel, and the segment code channel improves the fault tolerance, accuracy, and stability of the encoder. The design of the circle digital channel facilitates the acquisition of the number of rotations and simplifies the calculation process.

[0040] Furthermore, the image-type photoelectric encoder uses an image sensor and an image processing circuit to read position information through image acquisition and image recognition, thereby simplifying the calculation process and improving the response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are some embodiments of the present invention, not all embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor.

[0042] Figure 1 A schematic diagram of the structure of a vernier grating code disk provided by an embodiment of the present invention;

[0043] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0044] Figure 3 An image type photoelectric encoder architecture diagram provided for one embodiment of the present invention;

[0045] Figure 4 A schematic diagram of the phase angle of the main code track of a grating code disk provided for an embodiment of the present invention.

[0046] In the figure:

[0047] 1. Light source; 2. Grating code disk; 3. Image sensor; 4. Signal processing module;

[0048] 21, circle code channel; 22, segment code channel; 23, cursor code channel; 24, main code channel;

[0049] 41. Control circuit; 42. Time-to-digital converter; 43. Memory; 44. Image processing circuit; 45. Data output interface. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0052] Based on the problems existing in the prior art, the present invention provides a vernier grating code disk, an image photoelectric encoder and a position reading method. By changing the code disk structure and the encoding method, the absolute position reading of the image photoelectric encoder is achieved and the resolution is improved.

[0053] Figure 1 A schematic diagram of the structure of a vernier grating code disk provided by an embodiment of the present invention; Figure 2 for Figure 1 Enlarged view of point A in the middle; Figure 3 An image type photoelectric encoder architecture diagram provided for one embodiment of the present invention; Figure 4 A schematic diagram of the phase angle of the main code track of a grating code disk provided for an embodiment of the present invention.

[0054] View now Figure 1 and Figure 2 The embodiment of the present invention provides a vernier grating code disk, including a grating code disk 2, the grating code disk 2 is in the shape of a disc, and the grating code disk 2 is coaxially arranged with a main code track 24, a vernier code track 23, a segment code track 22 and a circle code track 21 in sequence from the outside to the inside on the periphery, and the number of engraved lines of each code track and the data length satisfy the following relationship:

[0055] M=2 UBL_S+UBL_N

[0056] N=2 UBL_S+UBL_N -1

[0057] S=2 UBL_S+UBL_N -2 UBL_N

[0058] Z=1

[0059] Wherein, M is the number of lines of the main code channel 24, N is the number of lines of the vernier code channel 23, S is the number of lines of the segment code channel 22, Z is the number of lines of the circle code channel 21, UBL_N is the data bit length obtained according to the phase difference between the vernier code channel 23 and the main code channel 24, and UBL_S is the data bit length obtained according to the phase difference between the segment code channel 22 and the main code channel 24;

[0060] The engraved lines of the circle digital track 21 and one of the engraved lines of the segment code track 22, the vernier code track 23 and the main code track 24 are all located on the same radius line of the grating code disk 2. The engraved lines of the segment code track 22, the vernier code track 23 and the main code track 24 and the engraved lines of the circle digital track 21 that are located on the same radius line of the grating code disk 2 are initial engraved lines.

[0061] In a specific implementation, the number of lines of the grating code disk 2, the cursor code track 23 and the segment code track 22 is set according to the accuracy requirement of the grating code disk 2. The accuracy of the grating code disk 2 is 2 n , then the number of lines on main code channel 24 is 2 n , that is, UBL_S+UBL_N=n; the number of lines of the main code channel 24 / cursor code channel 23 / segment code channel 22 is one of the following arrays: 16 / 15 / 12, 32 / 31 / 28, 64 / 63 / 56, 128 / 127 / 120, 256 / 255 / 240, 512 / 511 / 496, 1024 / 1023 / 992, 2048 / 2047 / 2016.

[0062] Taking n=8 as an example, the main code channel 24 has 256 light gap lines, the vernier code channel 23 has 255 light gap lines, the segment code channel 22 has 240 light gap lines, and the circle code channel 21 has 1 light gap line. The circle code channel 21 is used to confirm the number of rotations of the grating code disk 2.

[0063] See also Figure 3 The present invention also provides an image-type photoelectric encoder, including a grating code disk 2, a light source 1, a rotating shaft, an image sensor 3 and a signal processing module 4. The rotating shaft is vertically fixed to the center of the grating code disk 2. The light source 1 is arranged on one side of the grating code disk 2 and makes the light of the light source 1 opposite to the engraved lines of the code path of the grating code disk 2. The image sensor 3 is arranged on the other side of the grating code disk 2. When the grating code disk 2 rotates, the image sensor 3 obtains an image formed by the light of the light source 1 passing through the engraved lines of the grating code disk 2. The signal processing module 4 is connected to the image sensor 3 to obtain image data, processes the image data and calculates the rotation speed and angle information.

[0064] In some embodiments, the signal processing module 4 includes a control circuit 41, an image processing circuit 44, a memory 43, a time digital converter 42 and a data output interface 45; the control circuit 41 is connected to the image sensor 3, the image processing circuit 44, the memory 43 and the time digital converter 42, and the image processing circuit 44 is connected to the control circuit 41, the memory 43 and the data output interface 45; the control circuit 41 sends the image data and the time data calculated by the time digital converter 42 to the memory 43, and the image processing circuit 44 acquires the image data, performs image recognition through an image recognition algorithm, and calculates the rotation speed and angle information in combination with the time data.

[0065] In a specific implementation, the pixel size of the image sensor 3 needs to satisfy the following formula:

[0066]

[0067] Wherein, D is the side length of the pixel of the image sensor 3, θ0 is the minimum angle difference between the lines of the main code track 24, the vernier code track 23 and the segment code track 22 except the initial lines, and R is the radius of the grating code disk 2; to ensure that the image sensor 3 can distinguish any adjacent lines of the main code track 24, the vernier code track 23 and the segment code track 22.

[0068] The present invention also provides a position reading method of the above-mentioned image type photoelectric encoder, wherein the number of times the engraved lines of the circle digital track 21 of the grating code disk 2 pass through the image sensor 3 is used as the number of full circles of rotation of the grating code disk 2; the angle subdivision value of the main code track 24 and the vernier code track 23 of the grating code disk 2 is used as the coarse code for angle calibration, the angle subdivision value of the main code track 24 and the segment code track 22 is used as the sub-fine code for angle calibration, the signal angle value corresponding to the main code track 24 is used as the fine code for angle calibration, and the coarse code, the sub-fine code and the fine code are spliced ​​to obtain the angle rotated by the current position relative to the zero point, comprising the following steps:

[0069] Counting the number of times that the engraved lines of the circle digital track 21 of the grating code disk 2 pass through the image sensor 3 to obtain the number of full circles of the grating code disk 2;

[0070] Calculate the angle of the current position relative to the zero point, where the zero point is the position of the initial scale line.

[0071]

[0072] Where θ is the angle of the current position relative to the zero point, M, N, S are the number of lines of the main code channel 24, the cursor code channel 23 and the segment code channel 22 respectively; K M , K N , K S are the number of whole signal cycles that the main code channel 24, the cursor code channel 23 and the segment code channel 22 have rotated relative to the zero point at the current position; θ M ,θ N ,θ S They are the phase angles corresponding to the main code channel 24, the cursor code channel 23, and the segment code channel 22 in the current single signal cycle.

[0073] By transforming the above formula, we can get:

[0074] θ=(θ M -θ N )K MN +(θ M -θ S )K MS +θ M

[0075] Among them, θ M ,θ N ,θ SThey are the phase angles corresponding to the main code channel 24, the cursor code channel 23, and the segment code channel 22 in the current single signal cycle;

[0076] K MN and K MS They are different combinations of the number of whole signal cycles that the main code channel 24 and the vernier code channel 23 and the main code channel 24 and the segment code channel 22 have rotated relative to the zero point.

[0077] In the specific implementation, K MN Satisfies the following formula:

[0078] K MN =K M or K MN =K N

[0079] Among them, K M , K N Indicates the number of whole signal cycles that the main code channel 24 and the cursor code channel 23 have rotated relative to the zero point at the current position;

[0080] K MS Satisfies the following formula:

[0081] K MS =K S ,K S +1,...K M

[0082] Among them, K M , K S It indicates the number of whole signal cycles that the main code channel 24 and the segment code channel 22 have rotated relative to the zero point at the current position.

[0083] In some embodiments, the phase angle θ corresponding to the main code channel 24, the cursor code channel 23, and the segment code channel 22 in the current single signal cycle is calculated by the centroid method. M ,θ N ,θ S .

[0084] See also Figure 4 , with the phase angle θ corresponding to the main code channel 24 in the current single signal cycle M For example, OA' is the position of the M code line when it passes through the fixed pixel line, OA is the current position of the line, A and A' are the centroid positions of the M code line, which can be calculated by the following formula:

[0085]

[0086] Among them, L AB is the distance between the pixel line where point A is located and the fixed pixel line, L OA θ is the distance between the pixel line where point A is located and the center of the grating code disk 2.N ,θ S Similarly, it can be calculated.

[0087] In some embodiments, the rotation speed of the grating code disk 2 is calculated, and the number of whole signal cycles of the main code channel 24 within the time T is counted. The rotation speed of the grating code disk 2 is calculated by the following formula:

[0088]

[0089] Wherein, ω is the rotation speed of the grating code disk 2; B is the number of whole signal cycles of the main code channel 24 within the time T, and M is the number of engraved lines of the main code channel 24.

[0090] In some embodiments, the following step is also included: by scanning the grayscale value change on a column of the image sensor 3 or the grayscale value change on a suitable row, it is confirmed whether the engraved line of the circle digital track 21 of the grating code disk 2 passes through the image sensor 3.

[0091] In summary, the embodiments of the present invention provide a vernier grating code disk, an image-type photoelectric encoder, and a position reading method. The vernier grating code disk 2 applies the vernier principle to the grating code disk 2. Compared with the combination of multiple coarse code channels and one subdivided code channel, the code channel is more concise and the size of the code disk can be smaller. The design of the main code channel 24, the vernier code channel 23, and the segment code channel 22 improves the fault tolerance, accuracy, and stability of the encoder. The design of the circle digital channel 21 facilitates the acquisition of the number of rotations and simplifies the calculation process.

[0092] Furthermore, the image-type photoelectric encoder uses an image sensor 3 and an image processing circuit 44 to read position information through image acquisition and image recognition, thereby simplifying the calculation process and improving the response speed.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vernier grating code disc, It is characterized in that The grating code disk is in the shape of a disc, and the grating code disk is coaxially arranged with a main code track, a vernier code track, a segment code track and a circle code track in sequence from the outside to the inside on the periphery, and the number of engraved lines and the data length of each code track satisfy the following relationship: M＝2 UBL_S+UBL_N N＝2 UBL_S+UBL_N -1 S＝2 UBL_S+UBL_N -2 UBL_N Z＝1 Wherein, M is the number of lines of the main code channel, N is the number of lines of the vernier code channel, S is the number of lines of the segment code channel, Z is the number of lines of the circle code channel, UBL_N is the data bit length obtained according to the phase difference between the vernier code channel and the main code channel, and UBL_S is the data bit length obtained according to the phase difference between the segment code channel and the main code channel; The engraved lines of the circle digital track and one of the engraved lines of the segment code track, the vernier code track and the main code track are all located on the same radius line of the grating code disk. The engraved lines of the segment code track, the vernier code track and the main code track and the engraved lines of the circle digital track located on the same radius line of the grating code disk are initial engraved lines.

2. The vernier grating code disc according to claim 1, It is characterized in that The number of lines of the main code track, the vernier code track and the segment code track of the grating code disk is set according to the accuracy requirement of the grating code disk. The accuracy of the grating code disk is 2 n , then the number of lines on the main code channel is 2 n , that is, UBL_S+UBL_N=n; the number of lines of the main code channel / cursor code channel / segment code channel is one of the following arrays: 16 / 15 / 12, 32 / 31 / 28, 64 / 63 / 56, 128 / 127 / 120, 256 / 255 / 240, 512 / 511 / 496, 1024 / 1023 / 992, 2048 / 2047 / 2016.

3. An image type photoelectric encoder, It is characterized in that The invention comprises a vernier grating code disk as described in claim 1 or 2, a light source, a rotating shaft, an image sensor and a signal processing module, wherein the rotating shaft is vertically fixed to the center of the grating code disk, the light source is arranged on one side of the grating code disk and makes the light of the light source face the engraved lines of the code path of the grating code disk, the image sensor is arranged on the other side of the grating code disk, the image sensor obtains an image formed by the light of the light source passing through the engraved lines of the grating code disk when the grating code disk rotates, and the signal processing module is connected to the image sensor to obtain image data, processes the image data and calculates the rotation speed and angle information.

4. The image type photoelectric encoder according to claim 3, It is characterized in that The signal processing module includes a control circuit, an image processing circuit, a memory, a time-to-digital converter and a data output interface; the control circuit is connected to the image sensor, the image processing circuit, the memory and the time-to-digital converter, and the image processing circuit is connected to the control circuit, the memory and the data output interface; the control circuit sends the image data and the time data calculated by the time-to-digital converter to the memory, and the image processing circuit acquires the image data, performs image recognition through an image recognition algorithm and calculates the rotation speed and angle information in combination with the time data.

5. The image type photoelectric encoder according to claim 3, It is characterized in that The pixel size of the image sensor must satisfy the following formula: Where D is the side length of the pixel of the image sensor, θ 0 It is the minimum angle difference between the lines of the main code track, the vernier code track and the segment code track except the initial code line, and R is the radius of the grating code disk.

6. A method for reading the position of an image-type photoelectric encoder as claimed in claims 3 to 5, It is characterized in that The number of times the engraved lines of the circle digital track of the grating code disk pass through the image sensor is used as the number of full circles of the grating code disk; the angle subdivision value of the main code track and the vernier code track of the grating code disk is used as the coarse code for angle calibration, the angle subdivision value of the main code track and the segment code track is used as the sub-fine code for angle calibration, the signal angle value corresponding to the main code track is used as the fine code for angle calibration, and the coarse code, the sub-fine code and the fine code are spliced ​​to obtain the angle rotated by the current position relative to the zero point, including the following steps: Counting the number of times that the engraved lines of the circle digital track of the grating code disk pass through the image sensor to obtain the number of full circles of the grating code disk; Calculate the angle of the current position relative to the zero point. The zero point is the position of the initial scale line. It is calculated by the following formula: θ=(θ M -θ N )K MN +(θ M -θ S )K MS +θ M Among them, θ is the angle of the current position relative to the zero point, θ M ,θ N ,θ S They are the phase angles corresponding to the main code channel, the cursor code channel and the segment code channel in the current single signal cycle; K MN and K MS They are different combinations of the number of whole signal cycles that the main code channel and the cursor code channel, and the main code channel and the segment code channel have rotated relative to the zero point.

7. The position reading method of the image type photoelectric encoder according to claim 6, It is characterized in that The numbers of lines of the main code channel, the cursor code channel and the segment code channel are M, N and S respectively. K MN Satisfies the following formula: K MN =K M or K MN =K N Among them, K M , K N Indicates the number of whole signal cycles that the main code channel and the cursor code channel have rotated relative to the zero point at the current position; K MS Satisfies the following formula: K MS =K S ,K S +1,……K M Among them, K M , K S Indicates the number of whole signal cycles that the main code channel and segment code channel have rotated relative to the zero point at the current position.

8. The position reading method of the image type photoelectric encoder according to claim 6, It is characterized in that It also includes calculating the phase angle θ corresponding to the main code channel, the cursor code channel, and the segment code channel in the current single signal cycle by the centroid method. M ,θ N ,θ S .

9. The position reading method of the image type photoelectric encoder according to claim 6, It is characterized in that It also includes calculating the rotation speed of the grating code disk and counting the number of whole signal cycles of the main code channel within the time T. The rotation speed of the grating code disk is calculated by the following formula: Among them, ω is the rotation speed of the grating code disk; B is the number of whole signal cycles of the main code channel within the time T, and M is the number of lines of the main code channel.

10. The position reading method of the image type photoelectric encoder according to claim 6, It is characterized in that The method also includes the following steps: confirming whether the engraved lines of the circle digital track of the grating code disk pass through the image sensor by scanning the grayscale value changes on a certain column or a suitable grayscale value change on a certain row of the image sensor.

Images