A grating micro-displacement sensor

Abstract

The utility model discloses a grating micro displacement sensor, including fixed part and mobile part, and fixed part includes first PCB board and photocell, and photocell sets up on first PCB board, mobile part is connected in fixed part along longitudinal direction movably, and mobile part includes second PCB board, light source and reflection grating, and light source and reflection grating set up on second PCB board, and reflection grating is arranged in parallel with photocell, and the incidence angle of light source is arctan degree, and N is not less than 2, and light source emits light and reflects through reflection grating, and photocell receives the light signal of light and dark alternation that reflects through reflection grating and converts into electric signal. The utility model discloses through the design of oblique incidence light source, makes the moving distance of reflection spot on photocell and the longitudinal spacing variation between fixed part and mobile part form geometric amplification relation, converts tiny longitudinal displacement into the obvious lateral displacement signal on photocell, improves displacement detection sensitivity, can capture the more tinier longitudinal displacement change, and more saves longitudinal installation space.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, and specifically to a grating micro-displacement sensor. Background Technology

[0002] Currently, mainstream displacement sensors measure displacement by converting it into electrical signals. Examples include grating, magnetic grating, capacitive grating, and time-grating displacement sensors. Among these, grating displacement sensors are widely used, and their accuracy typically reaches about 3–5 micrometers. However, accuracy is mainly limited by the minimum scale line width and subdivision factor of the grating, thus limiting further improvements in accuracy. Figure 4 As shown, in traditional reflective displacement sensors, when the grating and the photovoltaic cell move relative to each other in the longitudinal direction, the amount of light spot movement and the amount of displacement are proportionally equal in a 1:1 ratio, which cannot amplify small displacements. In addition, the longitudinal (Z-direction) installation space is large, making it difficult to meet the needs of space-constrained scenarios and situations with short measurement lengths. This utility model proposes a new solution to the above problems. Utility Model Content

[0003] To overcome at least one of the aforementioned drawbacks, this invention provides a grating micro-displacement sensor. The objective of this invention can be achieved by employing the following technical solution: This application provides a grating micro-displacement sensor, comprising: The fixing part includes a first PCB board and a photovoltaic cell, wherein the photovoltaic cell is disposed on the first PCB board; A movable part, movably connected longitudinally to the fixed part, includes a second PCB board, a light source, and a reflective grating. The light source and the reflective grating are disposed on the second PCB board, and the reflective grating is arranged parallel to the photovoltaic cell. The incident angle of the light source is arctan(θ). The degree, where N is not less than 2, the light emitted by the light source is reflected by the reflective grating, and the photocell is used to receive the alternating bright and dark light signals reflected by the reflective grating and convert them into electrical signals.

[0004] In one possible implementation, the fixed part is mounted on a first mounting surface, the movable part is mounted on a second mounting surface, the second mounting surface is connected to the object under test, the movable part triggers the light spot displacement by changing the Z-direction distance with the fixed part, and the photocell converts the light spot displacement into an electrical signal with a 90° phase difference.

[0005] In one possible implementation, the light source is a parallel light emitter, N is an integer, and the light spot displacement and the spacing change are geometrically amplified.

[0006] In one possible implementation, the fixing part further includes a subdivision unit disposed on the first PCB board, the subdivision unit being used to perform subdivision calculations on the electrical signal.

[0007] In one possible implementation, the first PCB board is mounted on the first mounting surface by screws, and the second PCB board is mounted on the second mounting surface by screws.

[0008] In one possible implementation, the reflective grating has a periodically arranged etched structure for modulating incident light into alternating bright and dark stripes, wherein the etched period of the reflective grating is on the order of micrometers.

[0009] In one possible implementation, the fixing part further includes a first connector, which is disposed on the first PCB board and is used for signal transmission of the fixing part and connection with external circuitry.

[0010] In one possible implementation, the fixing part further includes a second connector, which is disposed on the second PCB board and is used for signal transmission of the moving part and connection to external circuitry.

[0011] In one possible implementation, the movable part further includes a base, the base including a first connecting plate and a second connecting plate connected at an angle, the first connecting plate being connected to the second mounting surface by screws, and the light source being disposed on the second connecting plate.

[0012] The beneficial technical effects of this utility model are as follows: According to the present disclosure, the grating micro-displacement sensor sets the light source to an oblique incidence mode at a specific angle, so that the moving distance of the reflected light spot on the photovoltaic cell forms a geometric amplification relationship with the change in the longitudinal distance between the fixed part and the moving part. When the longitudinal distance changes slightly, the light spot received by the photovoltaic cell will produce a significant displacement, thereby converting the small longitudinal displacement into an easily detectable lateral displacement signal on the photovoltaic cell, effectively improving the displacement detection sensitivity. The sensor can capture even smaller longitudinal displacement changes. At the same time, the use of a split longitudinal motion structure saves more longitudinal installation space compared with the traditional solution. Attached Figure Description

[0013] The following are given by way of example and without limitation in the accompanying drawings: Figure 1 A schematic diagram of the structure of the grating micro-displacement sensor according to an embodiment of the present invention is shown; Figure 2 This diagram illustrates the structure of the grating micro-displacement sensor when the second mounting surface moves close to the first mounting surface according to an embodiment of the present invention. Figure 3This diagram illustrates the structure of the grating micro-displacement sensor when the second mounting surface moves away from the first mounting surface according to an embodiment of the present invention. Figure 4 A schematic diagram of the structure of a displacement sensor in a conventional technology is shown.

[0014] In the figure: 100, first mounting surface; 200, second mounting surface; 1, fixed part; 2, moving part; 11, first PCB board; 12, photovoltaic cell; 13, subdivision unit; 14, first connector; 21, second PCB board; 22, light source; 23, base; 24, reflective grating; 25, second connector. Detailed Implementation

[0015] In the following detailed disclosure, these embodiments are fully described with reference to the accompanying drawings. In order to enable those skilled in the art to understand and clarify the technical solution of this utility model more clearly, the embodiments described below are not limited thereto. The present utility model will be further described in detail below with reference to the embodiments and the accompanying drawings.

[0016] In this utility model, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "join," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "join" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0017] In the description of this utility model, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0018] In a traditional grating displacement sensor, the photocell and scale grating are positioned along the Z-axis, and the scale grating also moves in the same direction. A light source passes through the grating and generates moiré fringes on the photocell. The photocell converts the optical signal into an electrical signal, such as... Figure 4 As shown, when the reflective grating is relatively displaced in the Z direction, the light source illuminates the photovoltaic cell through the reflective grating. For every 1 mm that the grating moves, the light spot moves 1 mm on the photovoltaic cell accordingly.

[0019] This application provides a grating micro-displacement sensor, such as Figures 1-3As shown, the device includes a fixed part 1 and a movable part 2. The fixed part 1 includes a first PCB board 11 and a photovoltaic cell 12, with the photovoltaic cell 12 disposed on the first PCB board 11. The movable part 2 is longitudinally movably connected to the fixed part 1. The movable part 2 includes a second PCB board 21, a light source 22, and a reflective grating 24. The light source 22 and the reflective grating 24 are disposed on the second PCB board 21, with the reflective grating 24 arranged parallel to the photovoltaic cell 12. The incident angle of the light source 22 is arctan(θ). The light emitted by the light source 22 is reflected by the reflective grating 24. The photocell 12 is used to receive the alternating bright and dark light signals reflected by the reflective grating 24 and convert them into electrical signals.

[0020] The grating micro-displacement sensor provided in this embodiment sets the light source 22 to an oblique incidence mode at a specific angle, so that the moving distance of the reflected light spot on the photovoltaic cell 12 forms a geometric amplification relationship with the change in the longitudinal distance between the fixed part 1 and the moving part 2. When the longitudinal distance changes slightly, the light spot received by the photovoltaic cell 12 will produce a significant displacement, thereby converting the small longitudinal displacement into a transverse displacement signal that is easily detected on the photovoltaic cell 12, effectively improving the displacement detection sensitivity. The sensor can capture even smaller longitudinal displacement changes. At the same time, the use of a split longitudinal motion structure saves more longitudinal installation space compared with the traditional solution.

[0021] In one possible implementation, such as Figures 1-3 As shown, the fixed part 1 is mounted on the first mounting surface 100, and the moving part 2 is mounted on the second mounting surface 200. The second mounting surface 200 is connected to the object under test. The moving part 2 triggers the light spot displacement by changing the distance between itself and the fixed part 1 in the Z direction. The photocell 12 converts the light spot displacement into an electrical signal with a phase difference of 90°.

[0022] In this process, by directly connecting the moving part 2 to the object under test, the minute longitudinal displacement of the object is directly converted into a change in the Z-axis spacing between the fixed part 1 and the moving part 2. This change in spacing triggers a lateral displacement of the light spot on the photovoltaic cell 12. Based on the principle of optical reflection, this geometric amplification of the longitudinal displacement into the lateral light spot displacement is achieved. The photovoltaic cell 12 then converts the amplified light spot displacement into an electrical signal with a 90° phase difference, providing a high-quality raw signal for subsequent subdivision circuits.

[0023] During the measurement process, the mechanical displacement is amplified and electrically isolated through two conversions (mechanical displacement → optical spot displacement → electrical signal), which not only ensures the measurement sensitivity but also avoids wear and interference caused by mechanical contact.

[0024] In one possible implementation, such as Figures 1-3 As shown, light source 22 is a parallel light emitter, N is an integer, and the light spot displacement and the spacing change are geometrically amplified.

[0025] By obliquely incidenting the parallel light source 22 onto the reflective grating 24 at a specific angle (such as arctan(1 / 2), arctan(1 / 3), etc.), the lateral displacement of the reflected light spot on the photovoltaic cell 12 is geometrically amplified in relation to the change in the longitudinal distance between the fixed part 1 and the moving part 2. When the longitudinal distance changes slightly, the light spot displacement is significantly amplified. Indirect amplification detection of the longitudinal displacement is achieved through optical reflection, ensuring the clarity and accuracy of the measurement signal.

[0026] The grating micro-displacement sensor provided in this application uses relative motion between the grating and the photocell 12 in the Z direction (perpendicular to the photocell 12 and the reflective grating 24), such as... Figure 1 As shown, the parallel light generated by the light source 22 shines on the reflective grating 24 and is reflected onto the photovoltaic cell 12. When the spacing changes, the light spot shining on the photovoltaic cell 12 will move on the photovoltaic cell 12.

[0027] Specifically, when the incident angle of the light source 22 is arctan(1 / 2) degrees, for every 1 mm increase or decrease in the spacing, the light spot on the photovoltaic cell 12 moves 2 mm to the left or right, which can improve the accuracy by 2 times; when the incident angle of the light source 22 is arctan(1 / 3) degrees, for every 1 mm increase or decrease in the spacing, the light spot on the photovoltaic cell 12 moves 3 mm to the left or right, which realizes the amplification of the small displacement and can improve the accuracy by 3 times.

[0028] It is understandable that N can be an integer or a non-integer. Both can be adjusted by changing the incident angle to ensure that the spot displacement and the change in longitudinal spacing are linearly amplified, thereby optimizing the detection sensitivity.

[0029] It is understandable that N can also be any other integer greater than 3. Using an integer N makes machining and assembly easier, and integer relationships can simplify optical and geometric calculations, making theoretical verification and engineering debugging easier. Integer multiples can avoid cumulative errors caused by non-integer angles, improve the long-term stability of the system, and make it more practical and reliable.

[0030] In one possible implementation, such as Figure 1 As shown, the fixing part 1 also includes a subdivision unit 13, which is disposed on the first PCB board 11 and is used to perform subdivision calculation on the electrical signal.

[0031] In this process, the light spot shining on the photovoltaic cell 12 generates relative motion with the photovoltaic cell 12. The photovoltaic cell 12 then converts this displacement signal into an electrical signal with a 90-degree phase difference. This electrical signal is further subdivided by a subdivision converter 13 for subsequent circuit processing. When the grating pitch is 20 μm and the incident angle of the light source 22 is arctan(1 / 2) degrees, only a 10,000-fold subdivision is needed to achieve nanometer-level displacement accuracy. This effectively improves the accuracy level of existing technologies and saves Z-axis installation space compared to traditional reflective displacement sensors, offering significant advantages in situations where measurement space is limited and the measurement length is short.

[0032] In one possible implementation, such as Figure 1 As shown, the first PCB board 11 is mounted on the first mounting surface 100 by screws, and the second PCB board 21 is mounted on the second mounting surface 200 by screws.

[0033] The first PCB board 11 and the second PCB board 21 are fixed to the first mounting surface 100 and the second mounting surface 200 respectively by screws, forming a stable mechanical connection structure. Screw fastening not only ensures the accurate positioning and rigid fixation of the two PCB boards on the mounting surfaces, effectively avoiding displacement deviations caused by vibration or external forces, but also ensures the stability of the Z-axis spacing change between the fixed part 1 and the moving part 2. This mechanical fixing method allows the light spot displacement signal to be accurately transmitted to the photocell 12, ensuring the reliability and repeatability of displacement detection.

[0034] In one possible implementation, the reflective grating 24 has a periodically arranged etched structure for modulating incident light into alternating bright and dark stripes, and the etched period of the reflective grating 24 is on the order of micrometers.

[0035] The micrometer-scale etched periodic reflective grating 24, through its precisely arranged periodic structure, modulates the incident parallel light into alternating bright and dark stripes at a specific angle. When the light source 22 illuminates the light obliquely, the reflective grating 24 can convert the longitudinal spacing change into the lateral displacement of the light spot, and form a detectable optical signal through the change in light intensity distribution of the alternating bright and dark stripes. The micrometer-scale etched structure not only ensures the directionality and stability of the alternating bright and dark stripes, but also amplifies the sensitivity of displacement detection through optical interference effect, so that the nanometer-scale longitudinal displacement change can be effectively captured by the photovoltaic cell 12 and converted into an electrical signal, realizing high-precision displacement measurement.

[0036] In one possible implementation, such as Figure 1 As shown, the fixing part 1 also includes a first connector 14, which is disposed on the first PCB board 11. The first connector 14 is used for signal transmission of the fixing part 1 and connection with external circuits.

[0037] By integrating the first connector 14 on the first PCB board 11, a standardized interface is provided for the signal transmission of the fixing part 1, so that the electrical signal output by the photovoltaic cell 12 can be stably and reliably transmitted to the external circuit or subsequent processing unit.

[0038] In one possible implementation, such as Figure 1 As shown, the fixing part 1 also includes a second connector 25, which is disposed on the second PCB board 21. The second connector 25 is used for signal transmission of the moving part 2 and connection with external circuits.

[0039] By integrating a second connector 25 on the second PCB board 21, a standardized interface is provided for the signal transmission of the moving part 2, so that the driving signal or auxiliary sensing signal of the light source 22 can be stably and reliably transmitted to the external control system.

[0040] In one possible implementation, such as Figure 1 As shown, the movable part 2 also includes a base 23, which includes a first connecting plate and a second connecting plate connected at an angle. The first connecting plate is connected to the second mounting surface 200 by screws, and the light source 22 is disposed on the second connecting plate.

[0041] The first connecting plate and the second connecting plate are connected by tilting to form a stable base 23. The first connecting plate and the second mounting surface 200 can be integrally formed to ensure the mechanical stability of the overall structure. The second connecting plate serves as the support platform for the light source 22, and its tilt angle optimizes the optical path layout.

[0042] The angle between the first connecting plate and the second connecting plate directly controls the incident direction of the light source 22. By adjusting the relative angle between the two connecting plates, the light projection path can be precisely controlled to meet specific precision detection requirements, thereby improving the flexibility of precision control.

[0043] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

[0045] In view of the detailed description above, these and other changes can be made to these embodiments. This written description includes embodiments of the best mode disclosed in this utility model. The patent scope of this utility model is defined by the claims, which are not limited by this disclosure. The protection scope of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope disclosed in this utility model, based on the technical solution and concept of this utility model, are within the protection scope of this utility model.

Claims

1. A grating micro-displacement sensor, characterized in that, include: The fixing part (1) includes a first PCB board (11) and a photovoltaic cell (12), the photovoltaic cell (12) being disposed on the first PCB board (11); A movable part (2) is longitudinally movably connected to the fixed part (1). The movable part (2) includes a second PCB board (21), a light source (22), and a reflective grating (24). The light source (22) and the reflective grating (24) are disposed on the second PCB board (21). The reflective grating (24) is disposed parallel to the photovoltaic cell (12). The incident angle of the light source (22) is arctan(22). The degree, where N is not less than 2, the light emitted by the light source (22) is reflected by the reflective grating (24), and the photocell (12) is used to receive the light signal with alternating light and dark reflected by the reflective grating (24) and convert it into an electrical signal.

2. The grating micro-displacement sensor according to claim 1, characterized in that, The fixed part (1) is installed on the first mounting surface (100), the moving part (2) is installed on the second mounting surface (200), the second mounting surface (200) is connected to the object to be tested, the moving part (2) triggers the light spot displacement by changing the distance between it and the fixed part (1) in the Z direction, and the photocell (12) converts the light spot displacement into an electrical signal with a phase difference of 90°.

3. The grating micro-displacement sensor according to claim 2, characterized in that, The light source (22) is a parallel light emitter, and N is an integer. The light spot displacement and the spacing change are geometrically amplified.

4. The grating micro-displacement sensor according to claim 1, characterized in that, The fixing part (1) also includes a subdivision unit (13), which is disposed on the first PCB board (11) and is used to perform subdivision calculation on the electrical signal.

5. The grating micro-displacement sensor according to claim 2, characterized in that, The first PCB board (11) is mounted on the first mounting surface (100) by screws, and the second PCB board (21) is mounted on the second mounting surface (200) by screws.

6. The grating micro-displacement sensor according to claim 1, characterized in that, The reflective grating (24) has a periodically arranged etched structure for modulating incident light into alternating bright and dark stripes, and the etched period of the reflective grating (24) is on the micrometer level.

7. The grating micro-displacement sensor according to claim 1, characterized in that, The fixing part (1) further includes a first connector (14), which is disposed on the first PCB board (11) and is used for signal transmission of the fixing part (1) and connection with external circuits.

8. The grating micro-displacement sensor according to claim 7, characterized in that, The fixed part (1) further includes a second connector (25), which is disposed on the second PCB board (21). The second connector is used for signal transmission of the moving part (2) and connection with external circuits.

9. The grating micro-displacement sensor according to claim 2, characterized in that, The movable part (2) also includes a base (23), which includes a first connecting plate and a second connecting plate connected at an angle. The first connecting plate is connected to the second mounting surface (200) by screws, and the light source (22) is disposed on the second connecting plate.

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