Absolute grating ruler and length measuring device

Abstract

The invention provides an absolute grating ruler and a length measuring device, and relates to the technical field of optical measurement, the absolute grating ruler comprises a main ruler used in cooperation with a code reader, the code reader moves in the length measuring direction of the main ruler, and the main ruler comprises a plurality of sub-rulers which are arranged in the displacement direction of the code reader at intervals; the auxiliary scale is arranged along the displacement direction of the code reader, the auxiliary scale is provided with at least one first absolute code channel used for positioning the position of a sub-scale corresponding to the code reader, and each sub-scale is provided with at least one incremental code channel used for reflecting the movement distance of the code reader on the sub-scale; and the code reader is used for reading the position of the corresponding sub-scale and the measured moving distance so as to obtain a length measurement result. And the first absolute code channel and the incremental code channel are combined to obtain a high-precision measurement length. And a plurality of sub-scales which are spliced at intervals are adopted, so that the mounting requirement and the requirement on the use environment are reduced, and batch production is facilitated.

Description

Technical Field

[0001] The present application relates to the field of optical measurement technology, and in particular to an absolute grating ruler and a length measuring device. Background Art

[0002] Currently known grating rulers are all set up in a whole strip. The processing technology of high-precision grating rulers generally uses photolithography, which is not suitable for grating rulers with a length of >30cm and the cost is very high. The cost of a one-meter grating ruler on the market is more than 300 yuan.

[0003] Long grating rulers also have a weakness in assembly, that is, the thermal expansion coefficient of the grating ruler does not match the thermal expansion coefficient of the mounting base, and the relative change over a long distance will produce a lot of stress. For example, the commonly used materials for high-precision grating rulers are glass or stainless steel, and the mounting base is preferably made of aluminum alloy. The difference in thermal expansion coefficient between the two can reach more than 10ppm / K. A temperature change of 10° will cause a length difference of 0.1mm at a distance of 1m. This puts a very big test on the installation process. If you are not careful, it will cause the grating ruler to break and fall off. Even if it does not fall off, it will cause unpredictable measurement errors. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide an absolute grating ruler and a length measuring device with high measurement accuracy, easy installation, low cost, and convenient mass production.

[0005] In one aspect of an embodiment of the present application, an absolute grating ruler is provided, comprising a main scale used in conjunction with a code reader, the code reader moves along the direction of length measurement of the main scale, the main scale comprises a plurality of sub-scales arranged and spaced apart along the displacement direction of the code reader, and a sub-scale arranged along the displacement direction of the code reader, at least one first absolute code track is arranged on the sub-scale for locating the position of the sub-scale corresponding to the code reader, at least one incremental code track is arranged on each of the sub-scales for reflecting the movement distance of the code reader on the sub-scale, and the code reader is used to read the position of the corresponding sub-scale and the measured movement distance to obtain a length measurement result.

[0006] Optionally, at least one second absolute code track is further provided on the sub-scale to locate the position of the incremental code track on the sub-scale.

[0007] Optionally, the code reader has an identification area for identifying the minimum continuous code channel area, and at least two identification areas are arranged on the code reader for identifying the code channel, and the two identification areas are respectively located at the two ends of the code reader along the displacement direction; the length of the sub-scale along the displacement direction is greater than the sum of the center distance between the two identification areas and the width of the identification area along the displacement direction, so that the two identification areas of the code reader can cover the same sub-scale at the same time, which is used for the code reader to calibrate the distance between the two identification areas on the absolute grating scale.

[0008] Optionally, the center distance between the two identification areas of the code reader is greater than the sum of the spacing distance between adjacent sub-scales and the width of the identification area, so that when the code reader is located in the spacing area between adjacent sub-scales, the two identification areas can simultaneously cover the code channels of adjacent sub-scales, so as to ensure the continuity of the readings when the code reader is in the spacing area.

[0009] Optionally, the code bar stripes of the incremental code channel are not perpendicular to the displacement direction of the code reader.

[0010] Optionally, the absolute code channel comprises a pseudo-random code.

[0011] Optionally, the absolute code channel includes at least two code channels which are arranged at equal intervals and whose total number of code bars differs by 1.

[0012] Optionally, the length of the secondary scale along the displacement direction is not less than the length of the main scale minus the period of the sub-scale.

[0013] In one aspect of an embodiment of the present application, a length measuring device is provided, comprising: a controller, a base, a code reader, and the above-mentioned absolute grating scale, wherein the absolute grating scale is fixed on the base, the code reader is arranged on the absolute grating scale, the code reader feeds back the code channel information of the absolute grating scale to the controller, and the length measurement result is outputted through the controller.

[0014] Beneficial effects of this application:

[0015] The absolute grating ruler and length measuring device provided in the embodiment of the present application can locate the sub-scale position of the current code reader through the first absolute code track of the sub-scale, that is, the first absolute code track of the sub-scale can locate the serial number of the sub-scale, and then obtain the moving distance of the code reader on the sub-scale through the incremental code track on the sub-scale. The first absolute code track and the incremental code track are combined to obtain a high-precision measurement length to ensure a small measurement error. The present application adopts a sub-scale with multiple splicing intervals, which can achieve the effect of reducing manufacturing costs, while reducing installation requirements and requirements for the use environment, and facilitating mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is one of the structural schematic diagrams of the absolute grating ruler provided in the embodiment of the present application;

[0018] Figure 2 This is the second structural schematic diagram of the absolute grating ruler provided in the embodiment of the present application.

[0019] Icon: 10-sub-scale; 101-incremental code channel; 102-second absolute code channel; 11-sub-scale; 110-first absolute code channel; 20-code reader; 201-identification area; L-length; D-width; T1-interval distance; T2-center distance; F1-displacement direction; F2-vertical direction. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0021] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0022] It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0023] In current production, sub-scalers are produced using a similar photolithography process, and it is impossible to produce any number of sub-scalers from a management perspective. Absolute scales require the ability to locate the current position arbitrarily, so it is necessary to be able to determine in real time which sub-scale the value currently read belongs to, but the information of the sub-scaler cannot meet this requirement.

[0024] Therefore, please refer to Figure 1 As shown, an embodiment of the present application provides an absolute grating ruler, which includes: a main scale used in conjunction with a code reader 20, the code reader 20 moves along the direction of length measurement of the main scale, the main scale includes a plurality of sub-scales 10 arranged and spaced along the displacement direction F1 of the code reader 20, and a sub-scale 11 arranged along the displacement direction F1 of the code reader 20, at least one first absolute code channel 110 is arranged on the sub-scale 11 for locating the position of the sub-scale 10 corresponding to the code reader 20, at least one incremental code channel 101 is arranged on each sub-scale 10 for reflecting the moving distance of the code reader 20 on the sub-scale 10, and the code reader 20 is used to read the position of the corresponding sub-scale 10 and the measured moving distance to obtain a length measurement result.

[0025] The main scale is generally mounted and fixed on the base, and the code reader 20 can be driven by the user's device under test and slide along the direction of the measured length on the main scale (displacement direction F1). Figure 1 The up and down directions in are perpendicular to the displacement direction F1.

[0026] from Figure 1 It can be seen that a row of sub-scales 10 are arranged in the upper area of ​​the main scale, and the multiple sub-scales 10 are arranged in sequence, and the adjacent sub-scales 10 are arranged at intervals. For example, the types of sub-scales 10 are less than the number of sub-scales 10, and a period can be formed by several sub-scales 10, and the multiple sub-scales 10 are installed on the same base. In some embodiments, the sub-scales 10 and the base can be fixed by glue bonding, and the position and amount of the bonding glue are symmetrical with the center of the sub-scale 10 to avoid the displacement of the center of the sub-scale 10 caused by the deformation of the glue.

[0027] A sub-scale 11 is disposed below the main scale. The length of the sub-scale 11 is not less than the length of the main scale minus the period of the sub-scale 10 . The period number of the sub-scale 10 can be determined using the first absolute code channel 110 of the sub-scale 11 .

[0028] Specifically, at least one first absolute code channel 110 is provided on the sub-scale 11, and at least one incremental code channel 101 is provided on each sub-scale 10. The code channel is a designed line or pattern, or a magnetic field distribution, or a dielectric constant distribution, or a conductivity coefficient distribution, and the minimum scale unit of the code channel is a bar code.

[0029] When the code reader 20 slides, it can read the first absolute code channel 110 on the secondary scale 11 and the incremental code channel 101 on the sub-scale 10. The code reader 20 feeds back the read code channel information to the controller, and the controller can calculate the length measurement result. The first absolute code channel 110 of the secondary scale 11 can be used to locate the sub-scale 10 position where the current code reader 20 is located, that is, the first absolute code channel 110 of the secondary scale 11 can locate the serial number of the sub-scale 10, and then the incremental code channel 101 on the sub-scale 10 is used to obtain the moving distance of the code reader 20 on the sub-scale 10. The first absolute code channel 110 and the incremental code channel 101 are combined to obtain a high-precision measurement length to ensure a small measurement error. The present application uses a sub-scale 10 with multiple splicing intervals, which can achieve the effect of reducing manufacturing costs, while reducing installation requirements and requirements for the use environment, and facilitating mass production.

[0030] The absolute code channel may be a pseudo-random code, for example Figure 1 On the secondary scale 11 shown, each code channel is of different lengths and is used for random encoding to achieve positioning of the sub-scale 10 .

[0031] It can also be Figure 2 The code channels shown as having at least two equal spacings and a total code bar number difference of 1 are called vernier codes.

[0032] For example Figure 2 In the figure, there are two rows of vernier codes on the secondary scale 11, and each row of vernier codes is evenly arranged at equal intervals. The left starting ends and the right ending ends of the two rows of vernier codes are aligned respectively, and there is a phase difference between the middle sections of the code channels of adjacent rows of vernier codes. Through the cooperation of the two rows of vernier codes and by comparing the phase difference of the two rows of vernier codes, the specific position of the current sub-scale 10 can be roughly determined, that is, the serial number of the sub-scale 10 can be determined, and the positioning of the sub-scale 10 can also be achieved.

[0033] Of course, more than two rows of vernier codes may be provided on the auxiliary scale 11 , for example, three rows, depending on actual needs.

[0034] On this basis, in order to further improve the measurement accuracy, at least one second absolute code track 102 can be set on the sub-scale 10 to locate the position of the incremental code track 101 on the sub-scale 10, and then the incremental code track 101 is subdivided.

[0035] Figure 1In addition to the incremental code channel 101, each sub-scale 10 is also provided with a second absolute code channel 102. As mentioned above, the function of the absolute code channel is positioning. The first absolute code channel 110 of the sub-scale 11 locates the sub-scale 10 where the code reader 20 is located, and the second absolute code channel 102 of the sub-scale 10 can further accurately locate the position area of ​​the incremental code channel 101 on the sub-scale 10 where the code reader 20 is located, that is, locate the serial number of the incremental code channel 101. Finally, the current position of the code reader 20 is accurately determined through the incremental code channel 101 of the sub-scale 10, thereby obtaining a more accurate length measurement result.

[0036] When the code reader 20 covers the main scale, it has an identification area 201 for identifying the minimum continuous code channel area. At least two identification areas 201 are arranged on the code reader 20 for identifying the code channel. The two identification areas 201 are respectively located at the two ends of the code reader 20 along the displacement direction F1. The length L of the sub-scale 10 along the displacement direction F1 is greater than the sum of the center distance T2 of the identification area 201 and the width D of the identification area 201 along the displacement direction F1, so that the two identification areas 201 of the code reader 20 can cover the same sub-scale 10 at the same time, which is used for the code reader 20 to calibrate the distance between the two identification areas 201 on the absolute grating scale.

[0037] The smallest continuous code area that can be identified by the code reader 20 is called an identification area 201. One sub-scale 10 is covered by two identification areas 201 at the same time. The thermal expansion and contraction of the code reader 20 itself can be accurately determined according to the change in the reading difference of the two identification areas 201. In other words, the reading difference of the two identification areas 201 of the code reader 20 on one sub-scale 10 can be used to calibrate the change of the distance between the two identification areas 201 on the absolute grating ruler with temperature and stress.

[0038] At the same time, if Figure 1 As shown, the center distance T2 between the two identification areas 201 of the code reader 20 is greater than the sum of the spacing distance T1 between adjacent sub-scales 10 and the width D of the identification area 201 along the displacement direction F1, so that when the code reader 20 is located in the spacing area between adjacent sub-scales 10, the two identification areas 201 can simultaneously cover the code tracks (the incremental code track 101 and the second absolute code track 102) of the adjacent sub-scales 10, so as to ensure the continuity of the reading when the code reader 20 is in the spacing area.

[0039] The two identification areas 201 of the code reader 20 can simultaneously cover the beginning and end segments of the code channels of adjacent sub-scales 10, measure the spacing distance T1 between adjacent sub-scales 10, and simultaneously complete the reading switching and distance measurement splicing when the code reader 20 passes through adjacent sub-scales 10, so that the read data is continuous and accurate.

[0040] In this way, when the center distance T2 between the two identification areas 201 of the code reader 20 is greater than the sum of the spacing distance T1 between adjacent sub-scales 10 and the width D of the identification area 201 along the displacement direction F1, when the code reader 20 crosses the spacing area of ​​adjacent sub-scales 10, at least one identification area 201 can work, and there must be two identification areas 201 that respectively identify two adjacent sub-scales 10, so that the phase position between the two sub-scales 10 can be determined according to the distance between the identification areas 201 obtained above, thereby completing the splicing of adjacent sub-scales 10, so that the code reader 20 can read the code channel information when it is located in the spacing area of ​​adjacent sub-scales 10, and the code reader 20 will not read empty. In this way, the reading of the code reader 20 is continuous, ensuring the accuracy of the final length measurement result.

[0041] In the example of the present application, the code bar stripes of the incremental code track 101 are not perpendicular to the displacement direction F1 of the code reader 20. The included angles between the code bar stripes of the incremental code track 101 and the displacement direction F1 are either greater than 90° or less than 90°.

[0042] That is, the incremental code track 101 is in the form of a diagonal grating, and the code reader 20 can compare the difference in the measurement results of the two diagonal code tracks to determine the distance that the displacement direction F1 of the code reader 20 deviates from the symmetry axis of the two incremental code tracks 101. This makes it possible to determine the position offset error of the two identification areas 201 on the code reader 20 in the vertical direction F2 within one sub-scale 10, and further determine the installation error and rotation angle of each sub-scale 10 in the vertical direction F2 of the code reader 20.

[0043] Through the above settings, the installation error of the device, thermal expansion and contraction during use, stress and strain, etc. can be deeply analyzed, greatly improving the measurement accuracy of the system. The above analysis results can be provided to users as functional safety data and processing error analysis to improve customer satisfaction.

[0044] On the other hand, based on the foregoing, the embodiment of the present application further provides a length measuring device, including: a controller, a base, a code reader 20, and the above-mentioned absolute grating scale, the absolute grating scale is fixed on the base, the code reader 20 is set on the absolute grating scale, the code reader 20 feeds back the code channel information of the absolute grating scale to the controller, and outputs the length measurement result through the controller.

[0045] The length measuring device comprises the same structure and beneficial effects as the absolute grating ruler in the aforementioned embodiment. The structure and beneficial effects of the absolute grating ruler have been described in detail in the aforementioned embodiment and will not be repeated here.

[0046] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An absolute grating ruler, characterized in that: include: A main scale used in conjunction with a code reader, the code reader moves in the direction of the measured length of the main scale, the main scale includes a plurality of sub-scales arranged and spaced along the displacement direction of the code reader, and a sub-scale arranged along the displacement direction of the code reader, at least one first absolute code track is arranged on the sub-scale for locating the position of the sub-scale corresponding to the code reader, at least one incremental code track is arranged on each of the sub-scales for reflecting the moving distance of the code reader on the sub-scale, and the code reader is used to read the position of the corresponding sub-scale and the measured moving distance to obtain a length measurement result.

2. The absolute grating ruler according to claim 1, characterized in that: At least one second absolute code track is also provided on the sub-scale to locate the position of the incremental code track on the sub-scale.

3. The absolute grating ruler according to claim 1 or 2, characterized in that: The code reader has an identification area for identifying the minimum continuous code track area. At least two identification areas are arranged on the code reader for identifying the code track, and the two identification areas are respectively located at the two ends of the code reader along the displacement direction; the length of the sub-scale along the displacement direction is greater than the sum of the center distance between the two identification areas and the width of the identification area along the displacement direction, so that the two identification areas of the code reader can cover the same sub-scale at the same time, which is used for the code reader to calibrate the distance between the two identification areas on the absolute grating ruler.

4. The absolute grating ruler according to claim 3, characterized in that: The center distance between the two identification areas of the code reader is greater than the sum of the spacing distance between adjacent sub-scales and the width of the identification area, so that when the code reader is located in the spacing area between adjacent sub-scales, the two identification areas can simultaneously cover the code channels of adjacent sub-scales, so as to ensure the continuity of the reading when the code reader is in the spacing area.

5. The absolute grating ruler according to claim 1 or 2, characterized in that: The code bar stripes of the incremental code channel are not perpendicular to the displacement direction of the code reader.

6. The absolute grating ruler according to claim 1 or 2, characterized in that: The absolute code channel includes pseudo-random coding.

7. The absolute grating ruler according to claim 1 or 2, characterized in that: The absolute code channel includes at least two code channels that are arranged at equal intervals and whose total number of code bars differs by 1.

8. The absolute grating ruler according to claim 1 or 2, characterized in that: The length of the secondary scale along the displacement direction is not less than the length of the main scale minus the period of the sub-scale.

9. A length measuring device, characterized in that: include: A controller, a base, a code reader, and the absolute grating ruler according to any one of claims 1 to 8, wherein the absolute grating ruler is fixed on the base, the code reader is arranged on the absolute grating ruler, the code reader feeds back the code channel information of the absolute grating ruler to the controller, and the controller outputs the length measurement result.

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