Position sensing system

Abstract

The invention provides a position sensing system. The position sensing system comprises a magnetic grid, a magnetic field sensing module and a data processing module. Based on the characteristics of a magnetic field formed by magnetic grid periodic magnetic poles, reference signals in one-to-one correspondence with Z-axis (perpendicular to a magnetic grid plane) positions are constructed to measure the motion / position of an object to be measured in the Z-axis direction. And the reference signals are obtained by calculating output signals of the corresponding magnetic field sensing modules through the data processing module. According to the position sensing system provided by the invention, due to the construction of the reference signal, the tiny movement / displacement of the to-be-measured object in the Z-axis direction can be measured; moreover, due to the structural characteristics of the magnetic grid, the reference signal is almost insensitive to the position of the magnetic field sensing module facing the magnetic grid, so that the position of the magnetic field sensing module does not need to be strictly limited, and the overall assembly precision requirement of the system is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of object positioning or motion detection of objects, and in particular to a position sensing system with low assembly precision requirement and based on magnetic field detection technology. BACKGROUND

[0002] The object position / motion sensing scheme based on magnetic field detection captures the magnetic field fingerprint of the position of the object through a sensor, determines the position of the object based on the corresponding relationship between the magnetic field and the spatial position, and then tracks the object or judges whether the position of the object is within a specific range. The related sensing scheme is widely used in fields such as physical buttons, screen touch, spatial positioning and tracking, and detection of micro motion / vibration.

[0003] Using magnetic field sensing to detect the position or motion of an object requires that the magnetic field and the spatial position within the sensing space have a one-to-one correspondence, which imposes strict requirements on the assembly position of the magnetic field sensing module. Because when the magnetic field sensing module deviates from the preset position / range (for example, assembly error or offset of the magnetic field sensing module during system operation), the position of the object cannot be accurately sensed. Therefore, the existing position / motion sensing system based on magnetic field detection technology usually needs to set up an additional limiting mechanism to strictly limit the movement of the magnetic field sensing module on a specific axis to ensure high assembly precision. Especially for micro displacement / motion detection systems, the size of the components that need to be assembled is often extremely small; under such conditions, it is difficult to ensure high assembly precision for the design, manufacture and assembly of sensing system components, and it is a challenge for the assembly of the sensing system. Therefore, how to meet the design requirements of a micro displacement / motion sensing system and not require high assembly precision has become an effort in the industry. SUMMARY

[0004] In order to provide a micro motion / micro displacement sensing system for touch or button, the present application uses the sensing output signal of the existing magnetic grid system to construct a reference signal, which is used to measure the micro motion / displacement in the direction perpendicular to the plane of the magnetic grid, and the reference signal is not sensitive to the position in the direction of the magnetic pole arrangement of the magnetic grid, thereby greatly reducing the precision requirement of the system assembly.

[0005] In some embodiments, the position sensing system provided by the present application includes a magnetic grid, a magnetic field sensing module, and a data processing module. The plane on which the upper surface of the magnetic grid is located is the XY plane, the magnetic pole arrangement direction of the magnetic grid is the X-axis direction, the object to be measured moves along the Z-axis direction, and the magnetic field sensing module is fixed on the object to be measured.

[0006] The magnetic field sensing module includes at least two half-bridges composed of magnetic resistors with the same sensing direction and parallel to the X-axis. The equivalent magnetic resistors on the two bridge arms of any of the two half-bridges are the same, and the magnetic resistors in all equivalent magnetic resistors need to be set in the same plane parallel to the XY plane; two half-bridge signals with a phase difference of 90 degrees are respectively drawn from the upper and lower bridge arms of the two half-bridges, and the output signal of the magnetic field sensing module includes the two half-bridge signals.

[0007] The data processing module determines the Z-axis position of the object to be measured based on the output signal of the magnetic field sensing module.

[0008] Furthermore, the data processing module determines the Z-axis position of the object to be measured, including: constructing a reference signal based on the output signal of the magnetic field sensing module , the reference signal The Z-axis position has a one-to-one correspondence within the sensing range; the reference signal is calculated in real time based on the output signal of the magnetic field sensing module The value of , and then calculate the Z-axis position of the object to be measured.

[0009] Furthermore, the two half-bridges form a full bridge. Preferably, the two half-bridges include four magnetic resistors spaced evenly apart in the X-axis direction; the two half-bridges include four magnetic resistors spaced evenly apart in the X-axis direction; the magnetic resistors on both arms of each half-bridge are identical and spaced apart by one pitch in the X-axis direction. Preferably, the pitch of the magnetic grating is less than 1 mm.

[0010] In some embodiments, the supply voltages of the two half-bridges are the same, and the reference signal is constructed based on the output signal of the magnetic field sensing module. , including: constructing a reference letter according to the following formula , is the supply voltage of the full bridge or the two half bridges, They are the two output signals respectively.

[0011] In another embodiment, the present application provides a position sensing system comprising: a magnetic grid, a magnetic field sensing module, and a data processing module. With the plane of the upper surface of the magnetic grid being the XY plane, the magnetic poles of the magnetic grid being arranged in the X-axis direction, and the object to be measured moving along the Z-axis direction, the magnetic field sensing module or the magnetic grid is fixed to the object to be measured.

[0012] The magnetic field sensing module comprises two full bridges. The equivalent magnetic resistances of each half-bridge within the two full bridges are identical in both bridge arms. The magnetic resistance sensing directions of all equivalent magnetic resistances are identical, parallel to the X-axis, and arranged in the same plane parallel to the XY plane. Two half-bridge signals, each 180 degrees out of phase, are drawn from the upper and lower bridge arms of each half-bridge within any full bridge to serve as differential output signals of the corresponding full bridges. The differential output signals of the two full bridges, each 90 degrees out of phase, serve as the output signals of the magnetic field sensing module. The data processing module determines the Z-axis position of the object to be measured based on the output signals of the magnetic field sensing module.

[0013] Accordingly, the reference signal is constructed based on the output signal of the magnetic field sensing module. , including: constructing a reference signal according to the following formula: , in, They are the two half-bridge output signals of one full bridge respectively. It is the two half-bridge output signals of another full bridge.

[0014] Furthermore, in the above two embodiments, the data processing module determines the current Z-axis position of the object to be measured, which is implemented as follows: , search for pre-stored reference signals Compare the relationship with the Z-axis position to obtain the Z-axis position of the current object to be measured; or, determine the calculated reference signal Whether it is greater than a preset threshold, thereby determining whether the Z-axis position of the object to be measured is within a preset first range. Simulation experiments show that the reference signals in the above two embodiments are within a range in the Z-axis direction. The position sensing system is insensitive to the position of the sensing module in the X-axis direction and has a one-to-one correspondence with the Z-axis coordinate, or even an approximately linear relationship. Obviously, for some application scenarios (for example, determining whether a button is pressed), the precise location of the button press is not necessary. Obviously, the position sensing system can be used for button press detection, measuring whether a button is micro-pressed or micro-touched.

[0015] Furthermore, the type of the magnetoresistance is XMR, which includes GMR, TMR, and AMR.

[0016] The position sensing system provided by the present invention constructs a reference signal based on the sensing output signals of an existing magnetic grating system. This reference signal is used to measure small movements / displacements perpendicular to the magnetic grating plane. Because this reference signal is insensitive to the position of the magnetic grating in the direction of its magnetic poles, the precision requirements for the magnetic field sensing module's assembly position relative to the magnetic grating's magnetic poles are reduced, significantly reducing the system's assembly precision requirements and improving system operational stability. Even if the magnetic field sensing module deviates along the X-axis, operation is not affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the composition of the position sensing system provided by the present invention.

[0018] Figure 2a In one embodiment, the magnetic field sensing module is located at Z=300um. 、 X-axis positions of the nine sampling points on the two output signals.

[0019] Figure 2b To correspond to Figure 2a At the 9 sampling points in the reference signal The relationship with the change of Z-axis coordinate (within the range of 150um-300um of Z-axis coordinate). DETAILED DESCRIPTION

[0020] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in a variety of different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely intended to represent selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0022] like Figure 1 As shown, the position sensing system provided by the application includes: a magnetic grid 101, a magnetic field sensor module 102 and a data processing module ( Figure 1 (not shown). The plane on which the upper surface of the magnetic grid 100 lies is defined as the XY plane, and the direction in which the magnetic poles of the magnetic grid 100 are arranged is defined as the X-axis direction. The object to be measured moves along the Z-axis direction, and the magnetic field sensing module 102 is fixed to the object to be measured to sense the displacement / motion of the object in the Z-axis direction.

[0023] The magnetic field sensing module 102 includes at least a full bridge or two half bridges composed of four magnetic resistors R1, R2, R3, and R4 arranged at equal intervals in the X-axis direction. The sensing directions of the magnetic resistors R1, R2, R3, and R4 are the same and parallel to the X-axis. In order to accurately measure the position of the object to be measured on the Z-axis, the four magnetic resistors R1, R2, R3, and R4 need to be arranged in the same plane parallel to the XY plane. The magnetic resistances on the two bridge arms of each of the two half bridges are the same, and two half bridge signals with a phase difference of 90 degrees are drawn from the upper and lower bridge arms of the two half bridges (for the magnetic resistances on the two bridge arms of each half bridge, the interval in the X-axis direction is one pitch, that is, the width of one magnetic pole). The output signal of the magnetic field sensing module 102 includes the two half bridge signals.

[0024] It should be noted that the magnetic resistance does not necessarily have to be a single physical magnetic resistance, but can be equivalent magnetic resistance, but the magnetic resistances in all equivalent magnetic resistances need to be arranged in the same plane parallel to the XY plane. The type of the magnetic resistance is XMR, which includes GMR, TMR, and AMR.

[0025] The data processing module determines the Z-axis position of the object to be measured based on the output signal of the magnetic field sensing module 102. The data processing module constructs a reference signal based on the output signal of the magnetic field sensing module 102. , the reference signal The reference signal is calculated in real time based on the output signal of the magnetic field sensing module 102. The value of , and then calculate the Z-axis position of the object to be measured.

[0026] exist Figure 1 In the embodiment shown, the magnetic field sensing module 102 is composed of the two half-bridges or one full-bridge, and the supply voltage of the two half-bridges is the same. The reference signal is constructed based on the output signal of the magnetic field sensing module. , including: constructing a reference letter according to the following formula , is the supply voltage of the full bridge or the two half bridges, Obviously, as long as the reference signal There is a one-to-one correspondence with the Z-axis coordinate, so the Z-axis coordinate of the object to be measured can be smoothly calculated (the object to be measured moves along the Z-axis direction).

[0027] for Figure 1In the embodiment shown, when the pitch of the magnetic grid 101 is 400 μm, the thickness is 370 μm, the magnetization intensity is 0.13 T, and the operating voltage of the magnetic field sensing module 102 is 5 V. Since the magnetic poles of the magnetic grid 101 are arranged periodically, its magnetic field is also periodic. In one magnetic field cycle, 9 sampling points (Pos1, Pos2, Pos3, ..., Pos9) are selected at equal intervals (intervals of 100 μm). At Z = 300 μm, 、 Two output signals such as Figure 2a As shown. Corresponding to the above 9 sampling points, the reference signal The relationship between the change of Z-axis coordinate (Z-axis coordinate within the range of 150um-300um) is as follows Figure 2b As shown. Figure 2b It can be seen that within a certain range in the Z-axis direction, the reference signal It has a one-to-one correspondence with the Z-axis coordinate, or even an approximately linear relationship. Figure 2b It can be seen that within a magnetic field cycle, no matter where the magnetic field sensing module is located on the X axis, its corresponding reference signal The curves tend to overlap with the position change of the Z-axis coordinate. Within a certain range in the Z-axis direction, the reference signal It is insensitive to the position of the magnetic field sensing module in the X-axis direction.

[0028] Obviously, according to the measurement principle of the magnetic grating sensor, two Figure 1 In the full bridge shown in FIG, the equivalent magnetic resistances of the two bridge arms of each half-bridge of the two full bridges are identical, the magnetic resistance sensing directions of all equivalent magnetic resistances are identical and parallel to the X-axis, and are arranged in the same plane parallel to the XY plane. Two half-bridge signals with a phase difference of 180 degrees are drawn from the upper and lower bridge arms of each half-bridge of any full bridge as the differential output signals of the corresponding full bridge. The differential output signals of the two full bridges have a phase difference of 90 degrees and serve as the output signals of the magnetic field sensing module. The data processing module determines the Z-axis position of the object to be measured based on the output signals of the magnetic field sensing module.

[0029] Accordingly, the reference signal is constructed based on the output signal of the magnetic field sensing module. , including: constructing a reference signal according to the following formula: , in, They are the two half-bridge output signals of one full bridge respectively. For the two half-bridge output signals of the other full bridge. Obviously, when the two half-bridge output signals of any full bridge differ by 180 degrees, its differential output is still a standard sine or cosine signal. It is only necessary to ensure that the differential output signals of the two full bridges ( )and( ) are 90 degrees apart and can be used directly Figure 1 、 Figure 2a 、 Figure 2b In addition, the supply voltages of the two full bridges do not have to be the same. When the supply voltages of the two full bridges are different, only an additional normalization process is required.

[0030] Furthermore, the reference signal The one-to-one correspondence with the Z-axis position is used to calculate the current Z-axis position of the object to be measured, which can be achieved in one of the following two ways: 1. Based on the calculated reference signal , search for pre-stored reference signals Compare the relationship with the Z-axis position to obtain the Z-axis position of the current object to be measured; 2. Determine the calculated reference signal Whether the Z-axis position of the object to be measured is within a preset first range is determined by determining whether the Z-axis position of the object to be measured is within a preset first range.

[0031] Obviously, for some application scenarios (for example, determining whether a button is pressed, determining whether a measurement button is slightly pressed or touched, and applications such as magnetic proximity switches), the precise location of the button press is not necessary. For these application scenarios, the second solution described above is more suitable, as it can avoid a large number of unnecessary calculations. For application scenarios such as micro-position tracking, the first solution described above can be used to accurately calculate the Z-axis position of the object to be measured.

[0032] The position sensing system provided by the present invention constructs a reference signal based on the sensing output signals of an existing magnetic grating system. This reference signal is used to measure small movements / displacements perpendicular to the magnetic grating plane. Because this reference signal is insensitive to the position of the magnetic grating in the direction of its magnetic pole arrangement, the precision requirements for assembly position in this direction are significantly reduced. Furthermore, even if the magnetic field sensing module deviates in the X-axis during system operation, normal operation is not affected, thereby improving system stability.

[0033] The foregoing description is merely an embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A position sensing system, characterized in that: The position sensing system includes: a magnetic grid, a magnetic field sensing module and a data processing module; The plane where the upper surface of the magnetic grid is located is the XY plane, the magnetic pole arrangement direction of the magnetic grid is the X-axis direction, the object to be measured moves along the Z-axis direction, and the magnetic field sensing module or the magnetic grid is fixed on the object to be measured; The magnetic field sensing module includes two half-bridges composed of equivalent magnetic resistances having the same sensing direction and being parallel to the X-axis. The equivalent magnetic resistances on the two bridge arms of each of the two half-bridges are the same, and the magnetic resistances of all the equivalent magnetic resistances need to be arranged in the same plane parallel to the XY plane. Two half-bridge signals with a phase difference of 90 degrees are drawn from the upper and lower bridge arms of the two half-bridges as output signals of the magnetic field sensing module. The data processing module determines the Z-axis position of the object to be measured based on the output signal of the magnetic field sensing module.

2. The position sensing system according to claim 1, wherein: The two half bridges constitute a full bridge.

3. The position sensing system according to claim 2, wherein: The two half-bridges include four magnetic resistors arranged at equal intervals in the X-axis direction; the magnetic resistors on the two bridge arms of each half-bridge in the two half-bridges are the same and are spaced apart by one pitch in the X-axis direction.

4. The position sensing system according to any one of claims 1 to 3, wherein: The data processing module determines the Z-axis position of the object to be measured, including: constructing a reference signal based on the output signal of the magnetic field sensing module , the reference signal There is a one-to-one correspondence with the Z-axis position within the sensing range; Calculate the reference signal in real time based on the output signal of the magnetic field sensing module The value of , and then calculate the Z-axis position of the object to be measured.

5. The position sensing system according to claim 4, wherein: The supply voltages of the two half-bridges are the same, and the reference signal is constructed based on the output signal of the magnetic field sensing module. , including: constructing a reference signal according to the following formula: ， in, is the supply voltage of the full bridge or the two half bridges, They are the two output signals respectively.

6. A position sensing system, characterized in that: The position sensing system includes: a magnetic grid, a magnetic field sensing module and a data processing module; The plane where the upper surface of the magnetic grid is located is the XY plane, the magnetic pole arrangement direction of the magnetic grid is the X-axis direction, the object to be measured moves along the Z-axis direction, and the magnetic field sensing module or the magnetic grid is fixed on the object to be measured; The magnetic field sensing module includes two full bridges, wherein the equivalent magnetic resistances on the two bridge arms of each half bridge of the two full bridges are the same, the magnetic resistance sensing directions of all the equivalent magnetic resistances are the same and are parallel to the X axis, and are arranged in the same plane parallel to the XY plane; two half bridge signals with a phase difference of 180 degrees are respectively drawn from the upper and lower bridge arms of each half bridge of any full bridge as the differential output signals of the corresponding full bridges, and the differential output signals of the two full bridges have a phase difference of 90 degrees and serve as the output signals of the magnetic field sensing module; The data processing module determines the Z-axis position of the object to be measured based on the output signal of the magnetic field sensing module.

7. The position sensing system according to claim 6, wherein: The reference signal is constructed based on the output signal of the magnetic field sensing module , including: constructing a reference signal according to the following formula: , They are the two half-bridge output signals of one full bridge respectively. It is the two half-bridge output signals of another full bridge.

8. The position sensing system according to claim 5 or 7, wherein: The data processing module determines the current Z-axis position of the object to be measured by: , search for pre-stored reference signals Compare the relationship with the Z-axis position to obtain the Z-axis position of the current object to be measured; or, determine the calculated reference signal Whether the Z-axis position of the object to be measured is within a preset first range is determined by determining whether the Z-axis position of the object to be measured is within a preset first range.

9. The position sensing system according to claim 7, wherein: The position sensing system is used to measure whether a key is slightly pressed or slightly touched.

10. The position sensing system according to claim 1, wherein: The type of the magnetoresistive resistor is XMR, which includes GMR, TMR, and AMR.

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