Contact type grating displacement sensor

Abstract

A contact type grating displacement sensor provided by the present invention comprises a housing, and a photoelectric detection chip, a probe and a driving mechanism which are arranged in the housing, the probe is provided with a scale grating, the driving mechanism drives the scale grating and the probe to move out of the housing along a measurement direction, and the photoelectric detection chip projects a light source to a corresponding area on the scale grating. The scale grating reflects an optical signal for representing a corresponding area back to the photoelectric detection chip, and the relative position relation between a light source projected by the photoelectric detection chip and the shell is fixed; the moving distance of the scale grating is determined according to an optical signal detected by the photoelectric detection chip, and the moving distance of the probe from the shell is determined according to the moving distance of the scale grating and the relative position relation between the scale grating and the probe, so that the distance between the fixed surface of the contact grating displacement sensor and the surface to be measured in the measuring direction is determined. According to the invention, the measuring range size ratio of the sensor probe breaks through the limitation of traditional 0.5, and the volume compression of the sensor is realized.

Description

Technical Field

[0001] The invention belongs to the field of displacement measurement, and in particular relates to a contact type grating displacement sensor. Background Art

[0002] With the increasing demand for displacement and matching status detection in application fields such as major strategic equipment and mechanical precision manufacturing, as long as there is gap, movement, and deformation, displacement sensors are needed for closed-loop control and detection. For example: motion control, gap and step measurement, parallelism and substrate warping detection, displacement measurement, etc. At present, high-precision displacement sensors have been widely used in precision manufacturing and processing, mechanical control and detection, etc., providing efficient measurement and monitoring tools for scientific research and industrial production in related fields, and have played a huge role, strongly promoting the development of related industries. At the same time, non-displacement parameters such as speed and pressure can be converted into displacement for measurement. Therefore, displacement sensors play an important role in the entire sensor measurement family. It is of great significance to develop high-performance displacement sensors with high resolution, small size and easy integration.

[0003] Among the many displacement measurement methods, grating displacement measurement is a method that uses the moiré fringes generated by the interference and diffraction of fine gratings under the illumination of light sources to convert displacement signals into alternating light intensity signals, and then outputs displacement changes through photoelectric elements such as photocells. Its measurement accuracy depends on the grating pitch of the grating. For example, the grating pitch of the grating can reach tens of microns or even smaller. Since its output signal basically has no high-order harmonics and can be subdivided by high frequency, it is suitable for high-precision and high-resolution measurement scenarios, and has good research value and application scenarios.

[0004] However, existing contact grating displacement sensors such as Figure 1 As shown, the scale grating is arranged in the sensor housing and the entire scale grating is always located in the housing during the measurement process, wherein the scale grating moves synchronously with the probe to determine the moving distance of the probe according to the detected moving distance of the scale grating, and the distance the probe moves out of the housing is limited by the length of the housing in the measuring direction (the scale grating length usually needs to occupy half of the internal length of the housing in the measuring direction, and the range of the displacement sensor is the length of the scale grating, that is, half of the internal length of the sensor in the measuring direction). In order to increase the moving distance of the probe and thus increase the range of the sensor, it is necessary to increase the length of the scale grating, and correspondingly, it is necessary to increase the length of the displacement sensor, which will increase the volume of the displacement sensor. It can be seen that the traditional contact grating displacement sensor has the problem of large volume, range size ratio less than 0.5, and the volume cannot be further compressed. Summary of the invention

[0005] The present invention provides a contact type grating displacement sensor to solve the problem that the current contact type grating displacement sensor has a large volume and cannot be further compressed.

[0006] According to a first aspect of an embodiment of the present invention, there is provided a contact grating displacement sensor, comprising a housing, a photoelectric detection chip, a probe and a driving mechanism arranged in the housing, the probe being provided with a scale grating, the driving mechanism driving the scale grating and the probe to move out of the housing along a measuring direction, the photoelectric detection chip projects a light source onto a corresponding area on the scale grating, the scale grating reflects a light signal used to characterize the corresponding area back to the photoelectric detection chip, and the relative position relationship between the light source projected by the photoelectric detection chip and the housing is fixed;

[0007] According to the light signal detected by the photoelectric detection chip, the moving distance of the scale grating is determined, and according to the moving distance of the scale grating and the relative position relationship between the scale grating and the probe, the distance moved by the probe from the housing is determined, thereby determining the distance between the fixed surface of the contact grating displacement sensor and the surface to be measured in the measuring direction.

[0008] In an optional implementation, the scale grating includes two gratings arranged in parallel along the measuring direction, one of which is a periodic grating, and the other is a non-periodic grating encoded to characterize different areas in the measuring direction; a light source unit and indicator gratings located on both sides of the light source unit are provided on one side of the photodetection chip facing the scale grating, and the photodetection chip projects the light source onto the two gratings in the scale grating through the light source unit;

[0009] The two-path grating reflects the corresponding light signal back to the indicating grating on the side where it is located, and the two-path light signals reflected back are respectively irradiated on the photoelectric detection chip through the corresponding indicating grating, and the photoelectric detection chip converts the two-path light signals into moiré fringe signals;

[0010] The contact grating displacement sensor also includes a peripheral drive circuit and a data processor of a photoelectric detection chip. The photoelectric detection chip is connected to the data processor via its peripheral drive circuit. The peripheral drive circuit filters, amplifies, subdivides and counts the moiré fringe signal. The data processor decodes the processed moiré fringe signal to obtain the moving distance of the scale grating. According to the moving distance of the scale grating and the relative position relationship between the scale grating and the probe, the distance moved by the probe from the housing is determined, thereby determining the distance between the fixed surface of the contact grating displacement sensor and the surface to be measured in the measuring direction.

[0011] In another optional implementation, the scale grating is engraved in the probe or fixed in a concave groove of the probe.

[0012] In another optional implementation, the measuring direction is assumed to be the left-right direction, the probe moves from left to right during measurement, a reset spring is provided between the drive mechanism and the right end of the housing along the measuring direction, and in an initial state, the drive mechanism and the scale grating are both located at their leftmost positions in the housing, and the reset spring is in a normal state;

[0013] When the driving mechanism drives the scale grating to move to the leftmost end of the scale grating and aligns with the light source, the driving mechanism stops working. Under the action of the reset spring, the driving mechanism drives the scale grating to move to its leftmost position in the housing and drives the probe to reset to its initial position.

[0014] In another optional implementation, the relative position relationship between the scale grating and the probe is adjustable during the measurement process;

[0015] Assuming that the measuring direction is the left-right direction, the probe moves from left to right during measurement, and a reset spring arranged along the measuring direction is provided between the driving mechanism and the right end of the housing. In the initial state, the driving mechanism and the scale grating are both located at their leftmost positions in the housing, and the reset spring is in a normal state; the process of the scale grating moving from its leftmost position in the housing to its leftmost end aligned with the light source is one round movement of the scale grating, and the moving distance of the round is L;

[0016] The driving mechanism drives the scale grating and the probe to move synchronously to the right until the scale grating moves to its leftmost end and is aligned with the light source. When one round of movement is completed, the driving mechanism drives the scale grating to move to its leftmost position in the housing under the action of the reset spring, and the relative distance between the scale grating and the probe increases by L. Thereafter, the scale grating enters the next round of movement, and the driving mechanism drives the scale grating and the probe to move synchronously to the right, and the cycle continues.

[0017] In another optional implementation, a probe that can be telescoped to the right along the measuring direction is fixed to the inner side of the bottom surface of the shell, and the base of an electric telescopic rod is fixed to the innermost telescopic part of the probe, and the electric telescopic rod can be telescoped to the left. The driving mechanism is fixedly connected to the support plate of the scale grating so that the driving mechanism moves synchronously with the scale grating; the top end of the inner rod of the electric telescopic rod is used to abut the driving mechanism so that the driving mechanism drives the probe to move out of the shell through the electric telescopic rod.

[0018] In another optional implementation, the light source is located at the right end of the housing.

[0019] In another optional implementation, a slide rail arranged along the measuring direction is provided on the inner side of the bottom surface of the housing, so that the driving mechanism can slide along the slide rail.

[0020] In another optional implementation, a controller is further included, the controller is connected to the drive mechanism and the electric telescopic rod respectively, in the initial state, the probe is in a fully retracted state, the drive mechanism and the scale grating are both located at the leftmost position in the housing, the inner rod top of the electric telescopic rod abuts against the drive mechanism, and the reset spring is in a normal state;

[0021] The controller controls the driving mechanism and the electric telescopic rod according to the following steps:

[0022] Step S1, controlling the driving mechanism to drive the scale grating to move synchronously to the right, and at the same time drive the probe to extend, so that the innermost telescopic part of the probe moves synchronously to the right;

[0023] Step S2, when it is detected that the driving mechanism drives the leftmost end of the scale grating to align with the light source, the driving mechanism is controlled to stop working, and under the action of the reset spring, the driving mechanism drives the scale grating to move to its leftmost position in the housing, and the electric telescopic rod is controlled to extend until the inner rod top of the electric telescopic rod abuts against the driving mechanism. At this time, the relative distance between the scale grating and the probe increases by L, where L is the moving distance of the scale grating from its leftmost position in the housing to its leftmost end aligned with the light source, and the process returns to step S1;

[0024] The data processor determines the distance the probe has moved from the housing by:

[0025] Step S10, determining the moving distance of the scale grating according to the light signal detected by the photoelectric detection chip;

[0026] Step S20, judging whether the scale grating has moved to its leftmost position according to the determined moving distance of the scale grating, if so, setting N++, where the initial value of N is 0 and an integer, and executing step S30; otherwise, executing step S30;

[0027] Step S30, determine whether the moving distance of the determined scale grating has not changed within the set time. If so, use N*L+the moving distance of the determined scale grating as the distance the probe moves out of the housing, and send a drive mechanism stop working signal to the controller; otherwise, return to execute step S10.

[0028] In another optional implementation, an in-position sensor is further included. When the driving mechanism moves to contact the in-position sensor, the in-position sensor determines that the leftmost end of the scale grating is aligned with the light source.

[0029] The beneficial effects of the present invention are:

[0030] 1. The present invention sets the scale grating on the probe, and allows the scale grating to move out of the housing along the measuring direction with the probe. Since the scale grating is no longer required to be completely in the housing during the measurement process, the scale grating can be moved outside the housing. Therefore, the moving distance of the probe is no longer limited by half of the inner length of the housing in the measuring direction. The range size ratio of the sensor probe breaks through the traditional limitation of 0.5 and is improved. In this way, the length of the housing in the measuring direction can be shortened while ensuring the range of the sensor probe, thereby compressing the volume of the sensor. The present invention uses different positions on the scale grating to characterize the moving distance of the probe. The probe moves The distance determination is highly accurate, and it can be seen that the present invention has a compact and simple structure, high measurement accuracy and reliability, and can perform high-precision measurement of the gap and mutual matching state of objects in a narrow and extreme environment; in addition, the present invention does not directly use the moving distance of the scale grating as the distance that the probe moves out of the housing, but determines the distance that the probe moves out of the housing based on the moving distance of the scale grating and the relative position relationship between the scale grating and the probe. Therefore, the relative position relationship between the scale grating and the probe can be adjusted to increase the distance that the probe can move out of the housing, thereby further compressing the sensor volume under the premise of ensuring the sensor range;

[0031] 2. The present invention integrates the light source and the indicator grating onto the side of the photoelectric detection chip facing the scale grating, which can simplify the system optical path and shorten the height of the sensor in the vertical direction, thereby further compressing the volume of the sensor;

[0032] 3. The present invention sets the scale grating inside the probe, which can protect the scale grating and improve the measurement reliability of the sensor;

[0033] 4. The present invention provides a reset spring between the driving mechanism and the right end of the housing, which can realize the reset of the entire sensor, and the reset process does not require the help of the driving mechanism, thereby reducing energy consumption;

[0034] 5. The present invention sets the probe to be retractable, and fixes the base of the electric telescopic rod on the innermost telescopic part of the probe, so that the relative position between the scale grating and the probe can be adjusted. Every time the scale grating completes a round of movement from left to right, the relative distance between the scale grating and the probe is increased by the distance of one round of movement of the scale grating. Before entering the next round of movement, the electric telescopic rod is extended until the top of its inner rod abuts against the driving mechanism to ensure that in the next round of movement, the driving mechanism can still synchronously drive the scale grating and the innermost telescopic part of the probe to move to the right. It can be seen that the scale grating can be used repeatedly back and forth to characterize different distances of the probe moved out of the outer shell, thereby greatly compressing the volume of the sensor while ensuring the sensor range. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1It is a partial structural schematic diagram of the existing contact grating displacement sensor of the present invention;

[0036] Figure 2 is a side perspective view of an embodiment of the contact type grating displacement sensor of the present invention;

[0037] Figure 3 This is an enlarged view of the positional relationship between the photoelectric detection chip and the scale grating of the present invention;

[0038] Figure 4 is a top view of an embodiment of the contact grating displacement sensor of the present invention;

[0039] Figure 5 It is a schematic structural diagram of an embodiment of a probe provided with a scale grating of the present invention;

[0040] Figure 6 It is a side perspective view of another embodiment of the contact grating displacement sensor of the present invention. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention and to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0042] In the description of the present invention, unless otherwise specified and limited, it should be noted that the term "connection" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection between two elements. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0043] See also Figure 2, is a side perspective view of an embodiment of a contact grating displacement sensor of the present invention. The contact grating displacement sensor may include a housing 1 and a photoelectric detection chip 2, a probe 3 and a driving mechanism 4 arranged in the housing 1. The probe 3 is provided with a scale grating 5. The driving mechanism 4 drives the scale grating 5 and the probe 3 to move out of the housing 1 along the measuring direction. The photoelectric detection chip 2 projects a light source to a corresponding area on the scale grating 5 (the projection area 6 of the light source is a signal detection area). The scale grating 5 reflects the light signal used to characterize the corresponding area back to the photoelectric detection chip 2. The relative position relationship between the light source projected by the photoelectric detection chip 2 and the housing 1 is fixed. According to the light signal detected by the photoelectric detection chip 2, the moving distance of the scale grating 5 is determined. According to the moving distance of the scale grating 5 and the relative position relationship between the scale grating 5 and the probe 3, the distance moved out of the probe 3 from the housing 1 is determined, thereby determining the distance between the fixed surface of the contact grating displacement sensor and the surface to be measured in the measuring direction.

[0044] Combination Figure 3 and Figure 4 As shown, the scale grating may include two gratings 51 and 52 arranged in parallel along the measuring direction, one of which is a periodic grating 51, and the other is a non-periodic grating 52 that is encoded and used to characterize different areas in the measuring direction; a light source unit and indicator gratings located on both sides of the light source unit are provided on the side of the photodetection chip 2 facing the scale grating, and the photodetection chip projects the light source onto the two gratings 51 and 52 in the scale grating through the light source unit; the two gratings 51 and 52 reflect the corresponding light signals back to the indicator gratings on their sides, and the two reflected light signals are respectively irradiated on the photodetection chip through the corresponding indicator gratings, and the photodetection signal converts the two light signals into moiré fringe signals.

[0045] The contact grating displacement sensor may also include a peripheral drive circuit and a data processor of a photoelectric detection chip, wherein the photoelectric detection chip is connected to the data processor via its peripheral drive circuit, and the peripheral drive circuit performs filtering, amplification, subdivision and counting processing on the moiré fringe signal; the data processor decodes the processed moiré fringe signal to obtain the moving distance of the scale grating, and determines the distance that the probe moves out of the housing according to the moving distance of the scale grating and the relative position relationship between the scale grating and the probe, thereby determining the distance between the fixed surface of the contact grating displacement sensor and the surface to be measured in the measuring direction. The present invention integrates the light source and the indicator grating onto one side of the photoelectric detection chip facing the scale grating, which can simplify the system optical path and shorten the height of the sensor in the vertical direction, thereby further compressing the volume of the sensor.

[0046] In this embodiment, Figure 1As shown, the peripheral drive circuit 7 can be arranged in the housing 1, the photoelectric detection chip 2 and the peripheral drive circuit 7 can be fixed on the inner side of the upper cover 8 of the housing 1, and the probe 3 provided with the scale grating 5 can be arranged on the inner side of the lower bottom of the housing 1. The housing 1 can also be provided with a cable outlet 9 for the line to pass through. In addition, assuming that the measuring direction is the left-right direction, the probe moves from left to right, and a reset spring arranged along the measuring direction is provided between the drive mechanism 4 and the right end of the housing 1. In the initial state, the drive mechanism and the scale grating are both located at their leftmost positions in the housing, and the reset spring is in a normal state. When the drive mechanism drives the scale grating to move to the leftmost end of the scale grating and align with the light source, the drive mechanism stops working. Under the action of the reset spring, the drive mechanism drives the scale grating to move to the leftmost position in the housing, and drives the probe to reset to the initial position. When the drive mechanism drives the scale grating to move to the leftmost end of the scale grating and align with the light source, the reset spring is in a compressed state. The present invention provides a reset spring between the drive mechanism and the right end of the housing, which can realize the reset of the entire sensor, and the reset process does not require the help of the drive mechanism, thereby reducing energy consumption. The drive mechanism can be a pulley, and a slide rail (not shown in the figure) is provided on the inner side of the bottom surface of the housing 1 along the measuring direction, so that the drive mechanism 4 can slide along the slide rail. Figure 5 As shown, the scale grating 5 can be engraved in the probe 3 or fixed in the concave groove of the probe 3. The present invention sets the scale grating in the probe, which can protect the scale grating and improve the reliability of sensor measurement.

[0047] As can be seen from the above embodiments, the present invention sets the scale grating on the probe, and allows the scale grating to move out of the housing along the measuring direction with the probe. Since the scale grating is no longer required to be completely in the housing during the measurement process, the scale grating can be moved outside the housing. Therefore, the moving distance of the probe is no longer limited by half of the internal length of the housing in the measuring direction (for example, the moving distance of the probe and the length of the scale grating can both be equal to the internal length of the housing in the measuring direction). The range size ratio of the sensor probe breaks through the traditional limitation of 0.5 and is improved. In this way, the length of the housing in the measuring direction can be shortened while ensuring the range of the sensor probe, thereby compressing the sensor volume. The moving distance of the probe is characterized by different positions on the grating, and the moving distance of the probe is determined with high accuracy. It can be seen that the present invention has a compact and simple structure, high measurement accuracy and reliability, and can perform high-precision measurement of the gap and mutual matching state of objects in a narrow and extreme environment; in addition, the present invention does not directly use the moving distance of the scale grating as the distance the probe moves out of the housing, but determines the distance the probe moves out of the housing based on the moving distance of the scale grating and the relative position relationship between the scale grating and the probe. Therefore, the relative position relationship between the scale grating and the probe can be adjusted to increase the distance that the probe can move out of the housing, thereby further compressing the sensor volume under the premise of ensuring the sensor range.

[0048] In the present invention, the relative position relationship between the scale grating and the probe can be adjusted in addition to being fixed. Assuming that the measuring direction is the left-right direction, the probe moves from left to right during measurement, and a reset spring arranged along the measuring direction is provided between the driving mechanism and the right end of the housing. In the initial state, the driving mechanism and the scale grating are both located at their leftmost positions in the housing, and the reset spring is in a normal state; the process of the scale grating moving from its leftmost position in the housing to its leftmost end aligned with the light source is one round of movement of the scale grating, and the moving distance of the round is L; the driving mechanism drives the scale grating and the probe to move synchronously to the right until the scale grating moves to its leftmost end aligned with the light source, and when one round of movement is completed, the driving mechanism drives the scale grating to move to its leftmost position in the housing under the action of the reset spring, and the relative distance between the scale grating and the probe increases by L, and then the scale grating enters the next round of movement, and the driving mechanism drives the scale grating and the probe to move synchronously to the right, and so on.

[0049] See also Figure 6 , is a side perspective view of another embodiment of the contact grating displacement sensor of the present invention. Figure 6 and Figure 1The difference of the contact grating displacement sensor shown is that a probe 3 which can be telescopic to the right along the measuring direction is fixed on the inner side of the bottom surface of the shell 1, and a base of an electric telescopic rod 11 is fixed on the innermost telescopic part of the probe 3, and the electric telescopic rod 11 can be telescopic to the left, and the driving mechanism 4 is fixedly connected to the support plate of the scale grating 5 so that the driving mechanism 4 moves synchronously with the scale grating 5; the inner rod top of the electric telescopic rod 11 is used to abut the driving mechanism 4, so that the driving mechanism 4 drives the probe 3 to move out of the shell 1 through the electric telescopic rod 11.

[0050] Figure 6 and Figure 1 The difference of the contact grating displacement sensor shown is that it can also include a controller, which is connected to the drive mechanism and the electric telescopic rod respectively. In the initial state, the probe is in a fully retracted state, the drive mechanism and the scale grating are both located at the leftmost position in the housing, the inner rod top of the electric telescopic rod abuts against the drive mechanism, and the reset spring is in a normal state;

[0051] The controller can control the driving mechanism and the electric telescopic rod according to the following steps:

[0052] Step S1, controlling the driving mechanism 4 to drive the scale grating 5 to move rightward synchronously, and at the same time drive the probe 3 to extend, so that the innermost telescopic part of the probe 3 moves rightward synchronously;

[0053] Step S2, when it is detected that the driving mechanism 4 drives the leftmost end of the scale grating 5 to align with the light source, the driving mechanism 4 is controlled to stop working, and under the action of the reset spring 10, the driving mechanism 4 drives the scale grating 5 to move to its leftmost position in the housing 1, and controls the electric telescopic rod 11 to extend until the inner rod top of the electric telescopic rod 11 abuts against the driving mechanism 4. At this time, the relative distance between the scale grating 5 and the probe 3 increases by L, and L is the moving distance of the scale grating from its leftmost position in the housing to its leftmost end aligned with the light source, and returns to step S1. In this step, the displacement sensor can also be an in-place sensor 12. When the driving mechanism moves to contact the in-place sensor, the in-place sensor determines that the leftmost end of the scale grating is aligned with the light source.

[0054] The data processor may determine the distance the probe has moved from the housing by:

[0055] Step S10, determining the moving distance of the scale grating according to the light signal detected by the photoelectric detection chip;

[0056] Step S20, judging whether the scale grating has moved to its leftmost position according to the determined moving distance of the scale grating, if so, setting N++, where the initial value of N is 0 and an integer, and executing step S30; otherwise, executing step S30;

[0057] Step S30, determine whether the moving distance of the determined scale grating has not changed within the set time. If so, use N*L+the moving distance of the determined scale grating as the distance the probe moves out of the housing, and send a drive mechanism stop working signal to the controller; otherwise, return to execute step S10.

[0058] As can be seen from the above embodiments, the present invention sets the scale grating on the probe, and allows the scale grating to move out of the housing along the measuring direction with the probe. Since the scale grating is no longer required to be completely in the housing during the measurement process, the scale grating can be moved outside the housing. Therefore, the moving distance of the probe is no longer limited by half of the internal length of the housing in the measuring direction (for example, the moving distance of the probe and the length of the scale grating can both be equal to the internal length of the housing in the measuring direction). The range size ratio of the sensor probe breaks through the traditional limitation of 0.5 and is improved. In this way, the length of the housing in the measuring direction can be shortened while ensuring the range of the sensor probe, thereby compressing the sensor volume. The moving distance of the probe is characterized by different positions on the grating, and the moving distance of the probe is determined with high accuracy. It can be seen that the present invention has a compact and simple structure, high measurement accuracy and reliability, and can perform high-precision measurement of the gap and mutual matching state of objects in a narrow and extreme environment; in addition, the present invention does not directly use the moving distance of the scale grating as the distance the probe moves out of the housing, but determines the distance the probe moves out of the housing based on the moving distance of the scale grating and the relative position relationship between the scale grating and the probe. Therefore, the relative position relationship between the scale grating and the probe can be adjusted to increase the distance that the probe can move out of the housing, thereby further compressing the sensor volume under the premise of ensuring the sensor range.

[0059] In addition, the present invention sets the probe to be retractable, and fixes the base of the electric telescopic rod on the innermost telescopic part of the probe, so that the relative position between the scale grating and the probe can be adjusted. Each time the scale grating completes a round of movement from left to right, the relative distance between the scale grating and the probe is increased by the distance of one round of movement of the scale grating. Before entering the next round of movement, the electric telescopic rod is extended until the top end of its inner rod abuts against the driving mechanism to ensure that in the next round of movement, the driving mechanism can still synchronously drive the scale grating and the innermost telescopic part of the probe to move to the right. It can be seen that the scale grating can be used repeatedly back and forth to characterize different distances of the probe moving out of the shell, thereby greatly compressing the volume of the sensor while ensuring the sensor range.

[0060] In the above embodiment, the edge of the probe can be higher than the surface of the scale grating to protect the scale grating, prevent scratching the grating surface, improve the grating rigidity, and reduce the deformation caused by the grating force. At the same time, the moving top of the probe can also be processed into an arc shape to improve the smoothness and stability of the probe extension and retraction.

[0061] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0062] It will be appreciated that the invention is not limited to the precise construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from its scope. The scope of the invention is governed solely by the appended claims.

Claims

1. A contact grating displacement sensor, characterized in that: The invention comprises a housing, a photoelectric detection chip, a probe and a driving mechanism arranged in the housing, wherein the probe is provided with a scale grating, and the driving mechanism drives the scale grating and the probe to move out of the housing along the measuring direction, the photoelectric detection chip projects a light source onto a corresponding area on the scale grating, and the scale grating reflects a light signal used to characterize the corresponding area back to the photoelectric detection chip, and the relative position relationship between the light source projected by the photoelectric detection chip and the housing is fixed; According to the light signal detected by the photoelectric detection chip, the moving distance of the scale grating is determined, and according to the moving distance of the scale grating and the relative position relationship between the scale grating and the probe, the distance moved by the probe from the housing is determined, thereby determining the distance between the fixed surface of the contact grating displacement sensor and the surface to be measured in the measuring direction.

2. The contact grating displacement sensor according to claim 1, characterized in that: The scale grating includes two gratings arranged in parallel along the measuring direction, one of which is a periodic grating, and the other is a non-periodic grating encoded to characterize different areas in the measuring direction; a light source unit and indicator gratings located on both sides of the light source unit are provided on a side of the photodetection chip facing the scale grating, and the photodetection chip projects the light source onto the two gratings in the scale grating through the light source unit; The two-path grating reflects the corresponding light signal back to the indicating grating on the side where it is located, and the two-path light signals reflected back are respectively irradiated on the photoelectric detection chip through the corresponding indicating grating, and the photoelectric detection chip converts the two-path light signals into moiré fringe signals; The contact grating displacement sensor also includes a peripheral drive circuit and a data processor of a photoelectric detection chip. The photoelectric detection chip is connected to the data processor via its peripheral drive circuit. The peripheral drive circuit filters, amplifies, subdivides and counts the moiré fringe signal. The data processor decodes the processed moiré fringe signal to obtain the moving distance of the scale grating. According to the moving distance of the scale grating and the relative position relationship between the scale grating and the probe, the distance moved by the probe from the housing is determined, thereby determining the distance between the fixed surface of the contact grating displacement sensor and the surface to be measured in the measuring direction.

3. The contact grating displacement sensor according to claim 1, characterized in that: The scale grating is engraved in the probe or fixed in a concave groove of the probe.

4. The contact grating displacement sensor according to claim 3, characterized in that: Assuming that the measuring direction is the left-right direction, the probe moves from left to right during measurement, and a reset spring arranged along the measuring direction is provided between the driving mechanism and the right end of the housing. In the initial state, the driving mechanism and the scale grating are both located at their leftmost positions in the housing, and the reset spring is in a normal state; When the driving mechanism drives the scale grating to move to the leftmost end of the scale grating and aligns with the light source, the driving mechanism stops working. Under the action of the reset spring, the driving mechanism drives the scale grating to move to its leftmost position in the housing and drives the probe to reset to its initial position.

5. The contact grating displacement sensor according to claim 1, characterized in that: During the measurement process, the relative position relationship between the scale grating and the probe is adjustable; Assuming that the measuring direction is the left-right direction, the probe moves from left to right during measurement, and a reset spring arranged along the measuring direction is provided between the driving mechanism and the right end of the housing. In the initial state, the driving mechanism and the scale grating are both located at their leftmost positions in the housing, and the reset spring is in a normal state; the process of the scale grating moving from its leftmost position in the housing to its leftmost end aligned with the light source is one round movement of the scale grating, and the moving distance of the round is L; The driving mechanism drives the scale grating and the probe to move synchronously to the right until the scale grating moves to its leftmost end and is aligned with the light source. When one round of movement is completed, the driving mechanism drives the scale grating to move to its leftmost position in the housing under the action of the reset spring, and the relative distance between the scale grating and the probe increases by L. Thereafter, the scale grating enters the next round of movement, and the driving mechanism drives the scale grating and the probe to move synchronously to the right, and the cycle continues.

6. The contact grating displacement sensor according to claim 5, characterized in that: A probe that can be telescoped to the right along the measuring direction is fixed to the inner side of the bottom surface of the shell, and a base of an electric telescopic rod is fixed to the innermost telescopic part of the probe, and the electric telescopic rod can be telescoped to the left. The driving mechanism is fixedly connected to the support plate of the scale grating so that the driving mechanism and the scale grating move synchronously; the top end of the inner rod of the electric telescopic rod is used to abut the driving mechanism so that the driving mechanism drives the probe to move out of the shell through the electric telescopic rod.

7. The contact type grating displacement sensor according to any one of claims 1 to 6, characterized in that: The light source is located at the right end of the housing.

8. The contact type grating displacement sensor according to any one of claims 4 to 6, characterized in that: A slide rail arranged along the measuring direction is provided on the inner side of the bottom surface of the shell, so that the driving mechanism can slide along the slide rail.

9. The contact type grating displacement sensor according to claim 7, characterized in that: It also includes a controller, which is connected to the drive mechanism and the electric telescopic rod respectively. In the initial state, the probe is in a fully retracted state, the drive mechanism and the scale grating are both located at the leftmost position in the housing, the inner rod top end of the electric telescopic rod abuts against the drive mechanism, and the reset spring is in a normal state; The controller controls the driving mechanism and the electric telescopic rod according to the following steps: Step S1, controlling the driving mechanism to drive the scale grating to move synchronously to the right, and at the same time drive the probe to extend, so that the innermost telescopic part of the probe moves synchronously to the right; Step S2, when it is detected that the driving mechanism drives the leftmost end of the scale grating to align with the light source, the driving mechanism is controlled to stop working, and under the action of the reset spring, the driving mechanism drives the scale grating to move to its leftmost position in the housing, and the electric telescopic rod is controlled to extend until the inner rod top of the electric telescopic rod abuts against the driving mechanism. At this time, the relative distance between the scale grating and the probe increases by L, where L is the moving distance of the scale grating from its leftmost position in the housing to its leftmost end aligned with the light source, and the process returns to step S1; The data processor determines the distance the probe has moved from the housing by: Step S10, determining the moving distance of the scale grating according to the light signal detected by the photoelectric detection chip; Step S20, judging whether the scale grating has moved to its leftmost position according to the determined moving distance of the scale grating, if so, setting N++, where the initial value of N is 0 and an integer, and executing step S30; Otherwise, execute step S30; Step S30, determine whether the moving distance of the determined scale grating has not changed within the set time. If so, use N*L+the moving distance of the determined scale grating as the distance the probe moves out of the housing, and send a drive mechanism stop working signal to the controller; otherwise, return to execute step S10.

10. The contact type grating displacement sensor according to claim 9, characterized in that: It also includes an in-place sensor. When the driving mechanism moves to contact the in-place sensor, the in-place sensor determines that the leftmost end of the scale grating is aligned with the light source.

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