An encoder based on an lc oscillation circuit

Abstract

This invention discloses an encoder based on an LC oscillation circuit, comprising a rotor and a sensing component stationary relative to the rotor. The rotor has a metal structure arranged circumferentially around its axis of rotation, and the metal area of ​​the metal structure varies periodically along its circumferential distribution. The sensing component includes an LC oscillation circuit composed of an inductor L and a capacitor C, which oscillates under the excitation of a pulse source. The inductor coil in the LC oscillation circuit is positioned above the rotor corresponding to the metal structure. As the rotor rotates, the inductor coil corresponds to different metal areas of the metal structure. Under the influence of different metal areas, the oscillating LC oscillation circuit generates different oscillation frequencies for sampling circuits. This invention utilizes a metal structure with periodically varying metal area distributed on the rotor, and simultaneously employs an LC oscillation circuit to sense the periodically varying metal area, realizing a novel encoder technology and providing a new direction for the future development of encoders.

Description

Technical Field

[0001] This invention belongs to the field of rotation detection technology, and in particular relates to an encoder based on an LC oscillation circuit. Background Technology

[0002] An encoder is a device that encodes signals, such as bitstreams or data, and converts them into a signal format that can be used for communication, transmission, and storage. Encoders convert angular displacement or linear displacement into electrical signals; the former is called a code disk, and the latter a code scale. Based on the readout method, encoders can be divided into two types: contact and non-contact.

[0003] Traditional non-contact rotary encoders use photoelectric rotary measuring devices, which directly convert the measured angular displacement into digital signals to realize the encoder function.

[0004] Based on the consideration and application of LC oscillation circuits, this application proposes to realize encoder functions using LC oscillation circuits, opening up a brand-new technical route in the field of encoders. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by proposing an encoder based on an LC oscillation circuit, utilizing the frequency calculation principle of an LC oscillation circuit and the principle that inductance is affected by metal.

[0006] An encoder based on an LC oscillation circuit includes a rotor and a sensing component stationary relative to the rotor. The rotor has a metal structure arranged circumferentially around its axis of rotation, and the metal area of ​​the metal structure varies periodically along its circumferential distribution.

[0007] The sensing component includes an LC oscillation circuit composed of an inductor L and a capacitor C, which will oscillate under the excitation of a pulse source;

[0008] In the LC oscillation circuit, the inductor is placed above the rotor at a position corresponding to the metal structure. As the rotor rotates, the inductor will correspond to different metal areas of the metal structure. Under the influence of different metal areas, the LC oscillation circuit in oscillation will generate different oscillation frequencies for the sampling circuit to sample.

[0009] In the aforementioned encoder based on an LC oscillation circuit, the metal structure is a circumferential metal grid structure composed of several metal sheets spaced apart and uniformly distributed around the rotating shaft, forming a metal structure in which the metal area is periodically varied along the circumference of the rotating shaft.

[0010] In the encoder based on the LC oscillation circuit described above, the metal structure is a segmented metal structure composed of several gradually changing metal sheets with uniformly spaced or continuously distributed around the rotating shaft.

[0011] The area of ​​each gradient metal sheet varies as a function along the circumferential distribution of the metal structure.

[0012] In the encoder based on the LC oscillation circuit described above, the metal area of ​​each gradient metal sheet changes linearly along the circumferential direction of the metal structure distribution.

[0013] The gradient metal sheet has a sickle-shaped structure.

[0014] In the encoder based on the LC oscillation circuit described above, the rotor has two metal structures arranged circumferentially around the shaft, one inner and one outer, and the sensing component includes two LC oscillation circuits, with the inductors of the two LC oscillation circuits corresponding to the metal structures at their respective positions.

[0015] As the rotor rotates, each LC oscillation circuit in oscillation has its own oscillation frequency change under the influence of the change in the metal area of ​​its corresponding metal structure, which is then sampled by the sampling circuit.

[0016] In the encoder based on the LC oscillation circuit described above, the inner and outer rings of metal structures are circumferential metal grid structures composed of several metal sheets; and the metal sheets of the inner and outer rings of metal grid structures are staggered.

[0017] Alternatively, there are two rings of metal structures: one ring is a circumferential metal grid structure composed of several metal sheets, and the other ring is a segmented metal structure composed of several gradually changing metal sheets distributed circumferentially along the axis of rotation.

[0018] In the encoder based on the LC oscillation circuit described above, several gradient metal sheets of the segmented metal structure are connected end to end in sequence so that the segmented metal structure changes linearly along its circumferential distribution direction, and has a periodic effect on the oscillation frequency of the corresponding LC oscillation circuit during rotation.

[0019] In the aforementioned encoder based on an LC oscillation circuit, the encoder further includes an LC oscillation reference circuit. The inductor coil of the LC oscillation reference circuit does not correspond to any metal structure. When the LC oscillation circuit corresponding to the metal structure is supplied with a pulse source, the LC oscillation reference circuit is simultaneously supplied with an equal pulse source so that the sampling circuit can sample the standard oscillation frequency, which serves as a reference for the oscillation frequency change of the LC oscillation circuit of the sensing element.

[0020] In the encoder based on the LC oscillation circuit described above, the sampling circuit includes an MCU with an AD sampling interface, and each LC oscillation circuit is connected to an AD sampling interface.

[0021] In the encoder based on the LC oscillation circuit described above, the sampling circuit includes at least one frequency comparison circuit. Each LC oscillation circuit corresponding to the metal structure is paired with an LC oscillation reference circuit, and the frequency comparison results of the two LC oscillation circuits are output to the MCU by the frequency comparison circuit.

[0022] The advantages of this invention are:

[0023] The encoder implemented in this solution adopts a completely new technical approach, providing a new direction for the future development of encoders;

[0024] This scheme distributes a metal structure with periodically varying metal area on the rotor, and uses an LC oscillation circuit to sense the periodically varying metal area, thereby realizing an encoder with a completely new technical approach.

[0025] This solution uses the principle of LC oscillation circuit being affected by metal area to realize encoder function, which has higher stability compared to photoelectric encoders that are easily affected by external factors such as ambient light, dust, and vibration.

[0026] This solution proposes a segmented linear metal structure composed of continuous gradient metal sheets, which has no limitation on the number of scales and almost no upper limit on measurement accuracy. Compared with photoelectric encoders that are affected by scales, it has a significant accuracy advantage.

[0027] This solution proposes a rotor structure that combines two metal structures, which can achieve high measurement accuracy while overcoming the accuracy problem at the joint caused by the metal structure used to achieve high measurement accuracy.

[0028] This solution proposes using an additional LC oscillation circuit to achieve a standard oscillation frequency, and using this standard oscillation frequency as a reference value for detecting changes in the oscillation frequency, thus effectively solving the problem of temperature drift. Attached Figure Description

[0029] Figure 1 This is the schematic diagram of an LC oscillator circuit;

[0030] Figure 2 This is a circuit block diagram of the encoder based on the LC oscillation circuit of the present invention;

[0031] Figure 3 This is a structural diagram of the encoder in Example 1;

[0032] Figure 4 This is a schematic diagram of the shape of the metal structure on the rotor in Embodiment 1;

[0033] Figure 5 This is a schematic diagram of the shape of the metal structure on the rotor in Embodiment 1. Figure 2 ;

[0034] Figure 6 This is a structural diagram of the encoder in Example 2;

[0035] Figure 7 This is a circuit block diagram of the encoder in Example 2;

[0036] Figure 8 This is a structural diagram of the encoder in Example 3;

[0037] Figure 9 This is a structural diagram of the encoder in Example 4;

[0038] Figure 10 This is a structural diagram of an encoder consisting of two metal structures as shown in Example 5;

[0039] Figure 11 This is a structural diagram of an encoder with another combination of two metal structures in Example 5;

[0040] Figure 12 This is a structural diagram of an encoder combining two metal structures as shown in Example 6;

[0041] Figure 13 This is a structural diagram of an encoder with another combination of two metal structures in Example 6;

[0042] Figure 14 The circuit structure diagram of the frequency comparison circuit provided by the present invention.

[0043] Reference numerals: Rotor 1; Induction component 2; Metal structure 3; Gradient metal sheet 31; LC oscillation circuit 4; Inductor coil 41; Pulse source 5; LC oscillation reference circuit 6; Inductor coil 61; Shaft 7; Sampling circuit 8; Lead wire 9. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0045] like Figure 1 As shown, an LC oscillator circuit is a circuit composed of an inductor L and a capacitor C, forming a frequency-selective network used to generate high-frequency sinusoidal signals. Its basic principle is as follows:

[0046] The LC oscillation formula is L is the inductance in Henry; C is the capacitance in Farad; fr is the output frequency in Hertz.

[0047] The above formula leads to the following two conclusions:

[0048] (1) If C remains constant and L decreases, the frequency will increase; if L increases, the frequency will decrease.

[0049] (2) If L remains constant and C decreases, the frequency will increase; if C increases, the frequency will decrease.

[0050] This solution aims to pioneer a new technical route in the field of encoders based on the aforementioned fundamental principles, and its main implementation methods are as follows:

[0051] like Figure 2 and Figure 3 As shown, the encoder includes a rotor 1 and a sensing element 2 that remains stationary relative to the rotor 1 for sensing the rotation of the rotor 1. The rotor 1 has a metal structure 3 arranged circumferentially around its axis of rotation 7, and the metal area of ​​the metal structure 3 varies periodically along its circumferential distribution.

[0052] The sensing component 2 includes an LC oscillation circuit 4 composed of an inductor L and a capacitor C, which will oscillate under the excitation of the pulse source 5;

[0053] In the LC oscillation circuit 4, the inductor coil 41 is placed above the rotor 1 at a position corresponding to the metal structure 3. As the rotor 1 rotates, the inductor coil 41 will correspond to different metal areas of the metal structure 3. Under the influence of different metal areas, the LC oscillation circuit 4 in oscillation will generate different oscillation frequencies for sampling circuit 8 to sample.

[0054] Different metal areas will have different effects on the LC oscillation circuit. The periodic variation of the metal area along the circumference of the metal structure allows the corresponding LC oscillation circuit to sense different metal parts located directly below it. When put into use, the pulse source 5 outputs high-frequency pulses to the LC oscillation circuit to generate oscillation, i.e., the theoretical oscillation frequency. When different metal areas are located directly below the coil, the LC oscillation circuit will exhibit different oscillation frequencies due to the influence of different metal areas. The sampling circuit 8 determines the rotation angle based on the sampled different oscillation frequencies.

[0055] Pulse source 5 can be implemented in various ways, as long as the requirements are met. For example, it can be implemented using a crystal oscillator, or it can be implemented using an MCU and a capacitor. In the latter case, the MCU needs to periodically send a high level to one end of the capacitor. The switching process of the capacitor between high and low will generate a pulse signal. The specifics will not be limited or elaborated here.

[0056] The sampling circuit 8 may include an MCU, which has a preset method for converting frequency changes to angles, so as to obtain angle data based on the acquired frequency changes, such as... Figure 3 The illustrated metal structure, assuming it has 36 metal sheets, means that each change in the oscillation frequency of the LC oscillator circuit represents a 10-degree rotation. Furthermore, processing circuits, such as amplifier circuits and filter circuits, can be connected between the sampling circuit and the LC oscillator circuit to ensure that the sampling circuit obtains a clearer signal.

[0057] The present solution will be described in detail below with reference to the accompanying drawings and several embodiments:

[0058] Example 1

[0059] like Figure 4 As shown, in this embodiment, the metal structure 3 is a circumferential metal grid structure composed of several metal sheets spaced apart and uniformly distributed along the circumference of the rotation axis 7. These metal sheets have identical shapes, such as rectangles, trapezoids, or other shapes, to form a metal structure 3 with a periodically varying metal area along the circumference of the rotation axis 7. In this example, the periodic distribution of the metal structure is: with metal - without metal - with metal - without metal...

[0060] The rotor 1 has a circular disc structure with a circular through hole in the center. Of course, the rotor is made of a non-metallic material that will not affect the LC oscillation circuit. Figure 4 The given metal structure 3 is designed to be close to the outer edge of the rotor 1. In practical use, it can also be adopted as follows: Figure 5 As shown, it is located near the inner edge of rotor 1.

[0061] Specifically, rotor 1 uses a PCB board, and metal sheets are printed on the PCB board to realize a rotor with a metal structure.

[0062] Furthermore, an inductor coil 41 is located above the rotor 1, which, together with a capacitor, forms an LC oscillation circuit 4. For example... Figure 3 As shown, the inductor coil 41 is located at the position corresponding to the metal structure 3, which is directly above the metal sheet. During the rotation of the rotor 1, the metal structure 3 also rotates, while the inductor coil 41 remains stationary. Therefore, directly below it, there will be alternating appearances of the metal sheet and blank areas. Since it is supplied with a pulse source, it will generate an oscillation frequency. The alternation of the metal sheet and blank area directly below it will have different effects on the oscillation frequency. When the metal sheet is directly below, the oscillation frequency is higher, while when the blank area is directly below, the oscillation frequency is lower. The sampling circuit will collect the high-low frequency transformation results, with each transformation representing a rotation angle.

[0063] The sampling circuit 8, pulse source 5, and other circuits can be set on the upper surface of the PCB board used to print the inductor coil 41, and the inductor coil 41 is printed on the lower surface of the PCB board. The sampling circuit 8, pulse source 5, and other circuits can also be connected to the inductor coil 41 through the lead wire 9.

[0064] The capacitor that forms an LC oscillation circuit with the inductor coil 41 can be placed on top of the PCB board on which the inductor coil 41 is printed, or it can be connected to the inductor coil 41 via lead 9, just like the sampling circuit 8 and the pulse source 5.

[0065] Example 2

[0066] This embodiment is similar to Embodiment 1, except that while Embodiment 1 uses a circumferential metal gate and one LC oscillator circuit, this embodiment proposes a structure with a circumferential metal gate and two LC oscillator circuits, as detailed below. Figure 6 As shown.

[0067] At this time, as Figure 7 As shown, in addition to an LC oscillation circuit 4, the encoder also includes an LC oscillation reference circuit 6. The LC oscillation reference circuit 6 has the same structure as the LC oscillation circuit 4 and is supplied with the same pulse source 5. The difference is that the inductor coil 61 of the LC oscillation reference circuit 6 does not correspond to the metal structure 3, that is, it is not affected by the rotation of the rotor 1.

[0068] During the sampling process, both oscillation circuits are supplied with the same pulse source and oscillate accordingly. Sampling circuit 8 simultaneously samples both LC oscillation circuits. Because LC oscillation circuit 4 is affected by the periodicity of the metal structure, the sampling circuit will sample a periodically changing oscillation frequency signal. LC oscillation reference circuit 6 is unaffected by the metal structure, and its sampled oscillation frequency remains unchanged. Sampling circuit 8 can use the oscillation frequency sampled from LC oscillation reference circuit 6 as a standard frequency, serving as a reference value for the change in the oscillation frequency of LC oscillation circuit 4. This allows for a more accurate determination of the periodicity of the inductor coil 4 under the influence of the metal structure.

[0069] Although the oscillation frequency of an LC oscillation circuit is theoretically fixed when supplied with a stable pulse source, the varying environments in which the encoder operates and the constant temperature changes will affect the oscillation frequency differently. Therefore, even with the same pulse source and the same LC oscillation circuit, different temperatures will result in different oscillation frequencies, even without the influence of metal. This embodiment uses a second inductor coil, which is unaffected by metal, as a reference standard. Since both inductors are at the same temperature, the effect of temperature drift can be offset by detecting the incremental temperature change.

[0070] Specifically, because the encoder structure itself is small, the metal structure 3 on the rotor 1 is also small, the metal pieces constituting the metal structure 3 are even smaller, and the inductor coil itself is also very small, it only has a measurable effect on the inductor coil 41 when the metal piece is directly opposite it. Therefore, it is only necessary to extend the PCB board where the inductor coil 41 is located radially inward or outward from the rotor to a position that no longer corresponds to the metal structure, and then place the inductor coil 61 in this extended portion so that it is no longer directly opposite the metal piece. Figure 6 The image shows one possible setup method.

[0071] Example 3

[0072] This embodiment is similar to Embodiment 1, except that the metal structure 3 in this embodiment is different from that in Embodiment 1. The metal structure in this embodiment is a segmented metal structure composed of several gradually changing metal sheets 31 with gradually changing metal areas that are continuously distributed around the rotating shaft 7 in the circumferential direction, with adjacent gradually changing metal sheets 31 connected end to end.

[0073] The metal area of ​​each gradient metal sheet varies functionally along the circumferential distribution direction of the metal structure 3, thus forming a metal structure 3 with a periodically varying metal area along the circumferential direction of the rotation axis 7.

[0074] Specifically, such as Figure 8 As shown, the gradient metal sheets have a sickle-shaped structure; the metal area of ​​each gradient metal sheet varies linearly along the circumference of the metal structure 3. The metal area of ​​the metal structure formed by the end-to-end connection of the gradient metal sheets 31 varies linearly in segments.

[0075] Preferably, the end of the gradient metal sheet 31 with the largest metal area corresponds to the largest amount of inductor coil 41. When it is directly below inductor coil 41, its influence on inductor coil 41 is greatest. Conversely, the end with the smallest metal area corresponds to the smallest amount of inductor coil 41. When it is directly below inductor coil 41, its influence on inductor coil 41 is minimal. Between the two ends, the metal area gradually changes, and correspondingly, its influence on inductor coil 41 also gradually changes. Figure 8 In this design, the inductor coil 41 is wound into a rectangle. The width of the end with the largest metal area of ​​the gradient metal sheet 31 is close to the length of the inductor coil 41. "Close" means it can be slightly larger or slightly smaller, with a difference of no more than 10%, almost perfectly corresponding to the entire inductor coil 41. The end with the smallest metal area is very narrow, corresponding only to a small portion of the inductor coil 41. Of course, in practical applications, the inductor coil does not necessarily have to be wound into a rectangle; it can also be in other shapes. This is not a limitation here.

[0076] In this embodiment, the metal area of ​​each metal sheet varies linearly, and its effect on the LC oscillation circuit 4 also varies linearly. Moreover, since the metal structure is composed of gradually changing metal sheets connected end to end, the entire metal structure is a piecewise linear structure, and its effect on the LC oscillation circuit 4 is also piecewise linear. Correspondingly, the change in the oscillation frequency of the LC oscillation circuit is also piecewise linear.

[0077] As rotor 1 rotates, the metal structure also rotates, while the position of inductor coil 41 remains stationary. Therefore, the area of ​​the metal directly below it changes linearly and periodically. Since it is connected to a pulse source, it generates an oscillation frequency. The linearly and periodically changing metal area appearing directly below it will have different effects on its oscillation frequency. When the maximum metal area of ​​a gradient metal sheet is located directly below it, the oscillation frequency is the highest. Subsequently, as rotor 1 rotates, the metal area of ​​the gradient metal sheet 31 located directly below inductor coil 41 will gradually decrease. This change is linear, so the oscillation frequency will also gradually decrease linearly until the minimum metal area of ​​the gradient metal sheet is reached. Then, another gradient metal sheet is placed corresponding to inductor coil 41, and the above process is repeated. By repeating this cycle, the rotation angle can be obtained. The sampling circuit will thus acquire the periodically linearly changing oscillation frequency. Each transition from one gradient metal sheet to another represents a large rotation angle. That is, the transition between segments of the piecewise linearized circuit represents a large rotation angle. Within the gradient metal sheet, the corresponding small rotation angle can be obtained based on the linear change of the oscillation frequency. In other words, within each linear segment, the small rotation angle can be obtained based on the linear change.

[0078] This example can not only detect the angle, but also determine the direction. Moreover, compared with the method in Embodiment 1 (where the detection accuracy is affected by the density of the metal sheets), the metal sheets can be set without gaps, thus achieving higher detection accuracy.

[0079] Example 4

[0080] This embodiment is similar to Embodiment 3, except that, as Figure 9 As shown, this embodiment, like Embodiment 2, proposes an LC oscillation reference circuit 6 for reference. That is, in addition to the LC oscillation circuit corresponding to the metal structure 3, it also has a second LC oscillation circuit, referred to here as the LC oscillation reference circuit 6. This LC oscillation reference circuit 6 has the same structure as the LC oscillation circuit 4 for detection and is supplied with the same pulse source 5. The difference is that the inductor coil 61 of this LC oscillation reference circuit 6 does not correspond to the metal structure 3, that is, it is not affected by the rotation of the rotor 1.

[0081] During the sampling process, both oscillation circuits are supplied with the same pulse source and oscillate accordingly. Sampling circuit 8 simultaneously samples both LC oscillation circuits. Because LC oscillation circuit 4 is affected by the periodicity of the metal structure, the sampling circuit will sample a piecewise linearly changing oscillation frequency signal. LC oscillation reference circuit 6 is unaffected by the metal structure, and its sampled oscillation frequency remains unchanged. This embodiment also uses a second inductor coil unaffected by the metal structure as a reference standard. Since both inductors are at the same temperature, detecting the effect by judging the increment can offset the influence of temperature drift, thus obtaining a more accurate result regarding the periodicity of the inductor coil 4 due to the metal structure.

[0082] Similarly, here we only need to move the PCB board where the inductor coil 41 is located radially inward or outward from the rotor to a position that no longer corresponds to the metal structure, and then place the inductor coil 61 in this extended portion so that it is not directly opposite the metal sheet. Figure 9 The image shows an example of an inward extension.

[0083] Example 5

[0084] This embodiment is similar to Embodiment 1 or Embodiment 3, except that this embodiment proposes to use a combination of two metal structures to improve detection accuracy, as detailed below:

[0085] The rotor 1 has two metal structures 3 arranged circumferentially around the shaft 7, one inner and one outer. The sensing component 2 includes two LC oscillation circuits 4, and the inductors 41 of the two LC oscillation circuits 4 correspond to one metal structure 3 respectively. As the rotor 1 rotates, each LC oscillation circuit 4 in oscillation has its own oscillation frequency change under the influence of the change in the metal area of ​​its corresponding metal structure 3, which is then sampled by the sampling circuit.

[0086] Figure 10 The diagram illustrates two schemes employing the metal structures described in Embodiment 1. Specifically, the inner and outer rings of metal structure 3 are circumferential metal grid structures composed of several metal sheets. When the rotor 1 rotates, the oscillation frequency of the corresponding LC oscillation circuit 4 changes. The change in the oscillation frequency of the inner ring corresponds to a change in the oscillation frequency of the outer ring. Furthermore, the inner and outer rings of metal sheets are staggered. As the rotor rotates, the oscillation frequencies of the inner and outer rings change sequentially. The angle through which the inner ring oscillation frequency changes to the outer ring oscillation frequency remains fixed. Therefore, the detection accuracy can be improved based on the changing logic.

[0087] Figure 11The diagram shows a better encoder structure that combines the two metal structure schemes of Embodiment 1 and Embodiment 3. Specifically, there are two rings of metal structures 3, one ring is a circumferential metal grid structure composed of several metal sheets, and the other ring is a metal structure 3 composed of several gradient metal sheets 31 distributed circumferentially along the rotating shaft 7. The circumferential metal grid structure can be on the outside and the metal structure composed of gradient metal sheets can be on the inside, or vice versa. This is not limited here.

[0088] Figure 11 Taking the latter as an example, the inductors 41 of the two LC oscillation circuits 4 correspond to the internal metal structure 3 and the external metal structure 3, respectively. When the rotor 1 rotates, the two metal structures rotate simultaneously, and the sampling circuit 8 samples the oscillation frequencies of the two LC oscillation circuits. The following uses... Figure 11 Taking the combination method as an example, the inner ring refers to the circumferential metal grid structure, and the outer ring is a segmented metal structure composed of gradient metal sheets. The rotation direction can be determined based on the outer ring. However, since the outer ring has higher accuracy than the inner ring, and adjacent gradient metal sheets on the outer ring are connected end-to-end, there can be inaccurate judgments at the joints. This embodiment combines the two metal structure schemes in an inner-outer combination manner. The inner ring can be used for coarse judgment, and the outer ring for fine judgment. The inner ring compensates for the accuracy problems at the joints of the outer ring, while the outer ring determines the direction. In other words, the encoder implemented in this embodiment not only has high detection accuracy but can also determine the rotation direction of the target.

[0089] Example 6

[0090] This embodiment is similar to Embodiment 5, except that, like Embodiment 2, it includes a reference LC oscillation circuit 6. Specifically, in addition to the LC oscillation circuits corresponding to the two metal structures 3, a third LC oscillation circuit, referred to here as the LC oscillation reference circuit 6, is provided. This LC oscillation reference circuit 6 has the same structure as the two detection LC oscillation circuits 4 and is supplied with the same pulse source 5. The pulse source 5 for each LC oscillation circuit 4 can be the same or different, as long as the same pulse source is provided to the LC oscillation circuits; preferably, the same pulse source is used.

[0091] Similarly, the inductor 61 of this third LC oscillation circuit does not correspond to any metal structure, such as Figure 12 and 13 As shown, no matter how the rotor rotates, there will never be any metal below the inductor coil 61, and it will never be directly opposite the metal.

[0092] During the sampling process, the three LC oscillation circuits are supplied with the same pulse source and oscillate accordingly. Sampling circuit 8 simultaneously samples all three LC oscillation circuits. Since two of the LC oscillation circuits (4) are affected by the periodicity of the metal structure, the sampling circuit will sample periodically changing oscillation frequency signals. If the inductor coil of the oscillation circuit corresponds to a circumferential metal grid structure, the sampling circuit will sample a periodically changing oscillation frequency with alternating high and low frequencies. If the inductor coil of the oscillation circuit corresponds to a metal structure composed of gradient metal sheets, the sampling circuit will sample a piecewise linearly changing oscillation frequency signal. The third LC oscillation circuit—the LC oscillation reference circuit 6—is not affected by the metal structure, and its sampled oscillation frequency remains unchanged. Sampling circuit 8 can use the oscillation frequency sampled from the LC oscillation reference circuit 6 as a standard frequency. By using three identical LC oscillation circuits and ensuring they are operating at the same temperature, the oscillation frequency of the third LC oscillation circuit, which is unaffected by the metal structure, can be used as a reference value for the oscillation frequency changes of the two periodically changing LC oscillation circuits affected by the metal structure, thus solving the problem caused by temperature drift.

[0093] Furthermore, in this scheme, the sampling of the LC oscillation circuit 4 in the sensing component 2 can be directly implemented by the AD sampling interface of the MCU. Of course, if there is a processing circuit including amplification circuit, filtering circuit and other circuits, it is connected to the AD sampling interface of the MCU through the processing circuit, and the MCU directly performs AD sampling on the LC oscillation circuit.

[0094] In the example with LC oscillation reference circuit 6, the MCU's AD sampling interface can also sample each LC oscillation circuit. The oscillation frequency obtained through LC oscillation reference circuit 6 is used as the standard frequency at each sampling moment. The MCU performs temperature drift correction on the change of oscillation frequency based on this standard frequency. For example, if the standard frequency obtained at a certain moment is A, and the oscillation frequency of LC oscillation circuit 4 corresponding to the metal structure is B, then its actual change due to the influence of the metal should be BA.

[0095] Alternatively, a frequency comparison circuit can be used. Each LC oscillation circuit 4 corresponding to the metal structure 3 is paired with an LC oscillation reference circuit 6, and a frequency comparison circuit is used to compare the frequencies of the two LC oscillation circuits 4 and output the result to the MCU. In scenario one or three, there is one frequency comparison circuit; in scenario five, there are two frequency comparison circuits. The principle of one or two frequency comparison circuits is similar. The principle of one circuit will be explained below using one circuit as an example.

[0096] Frequency comparator circuit, such as Figure 14As shown, its working principle is as follows: The two input signal terminals F1 and F2 are connected to LC oscillation circuits 4 and 6 respectively, so that the frequency signals of the two oscillation circuits are input to the frequency comparison circuit. One input signal discharges capacitor C4, and the other charges capacitor C4. In the resting state, capacitor C4 will be charged to half its voltage through the voltage divider composed of R3 and R4. In use, the frequency signal at terminal F1 is supplied to the base of transistor T1. Transistor T1 will switch according to the input frequency, and then generate a series of pulses corresponding to the input signal frequency. These pulses are used to control transistor T2, which continues to switch, thus allowing C4 to discharge at the frequency of input F1 pulses. Input F2 on the T4 side drives another diode pump composed of T3, C6, and D2, and charges C4 with short pulses corresponding to the frequency of input F2. If the two input frequencies are the same, the charging and discharging cycles of C4 will be the same, and therefore the voltage level through C4 will be equal to half the power supply voltage. If the frequency of input F1 is lower than the frequency of input F2, then the voltage through capacitor C4 will be higher than half the power supply voltage. If the frequency of input F1 is higher than the frequency of input F2, then the voltage through capacitor C4 will be less than half of the power supply voltage. The two input terminals of the frequency comparison circuit are connected to one end of the capacitor in LC oscillation circuit 4 and one end of the capacitor in LC oscillation circuit 6, respectively. Two oscillation frequencies are obtained through the aforementioned principle, and the comparison output result is output to the MCU. At this time, the MCU receives the result after temperature drift correction.

[0097] The specific embodiments described in this example are merely illustrative of the spirit of the invention. Those skilled in the art can make various modifications or additions to the described embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. An encoder based on an LC oscillation circuit, characterized in that, The device includes a rotor (1) and a sensing component (2) that is stationary relative to the rotor (1). The rotor (1) has two rings of metal structures (3) arranged circumferentially around its axis (7), and the metal area of ​​each ring of metal structure (3) varies periodically along its circumferential distribution. The sensing component (2) includes two LC oscillation circuits (4) composed of inductors L and capacitors C. The LC oscillation circuits (4) will oscillate under the excitation of a pulse source (5). The inductor coils (41) of the two LC oscillation circuits (4) correspond to one ring of metal structure (3) respectively. The inductor coil (41) in the LC oscillation circuit (4) is placed at the position corresponding to the rotor (1) and the corresponding metal structure (3). As the rotor (1) rotates, each LC oscillation circuit (4) in oscillation has its own oscillation frequency change under the influence of the change in the metal area of ​​its corresponding metal structure (3) for sampling circuit (8) to sample. The inner and outer rings of metal structure (3) consist of a circumferential metal grid structure and a segmented metal structure. The segmented metal structure is composed of several gradually decreasing or increasing metal sheets (31) that are continuously distributed around the rotating shaft (7) in the circumferential direction. The several gradually decreasing metal sheets are connected end to end in sequence so that the segmented metal structure changes in a segmented linear manner along its circumferential distribution direction, and has a periodic effect on the oscillation frequency of the corresponding LC oscillation circuit in the rotation process. The circumferential metal grid structure is composed of several metal sheets that are circumferentially spaced and evenly distributed around the rotating shaft (7); The encoder also includes an LC oscillation reference circuit (6), and the inductor (61) of the LC oscillation reference circuit (6) does not correspond to any metal structure (3). When the LC oscillation circuit (4) corresponding to the metal structure (3) is powered by a pulse source (5), the LC oscillation reference circuit (6) is simultaneously powered by an equal pulse source (5) so that the sampling circuit (8) can sample the standard oscillation frequency as a reference for the oscillation frequency change of the LC oscillation circuit (4) of the sensing element (2).

2. The encoder based on an LC oscillation circuit according to claim 1, characterized in that, The gradient metal sheet (31) has a sickle-shaped structure.

3. The encoder based on an LC oscillation circuit according to claim 1, characterized in that, The sampling circuit (8) includes an MCU with an AD sampling interface, and each LC oscillation circuit (4) is connected to an AD sampling interface.

4. The encoder based on an LC oscillation circuit according to claim 1, characterized in that, The sampling circuit (8) includes at least one frequency comparison circuit. Each LC oscillation circuit (4) corresponding to the metal structure (3) is associated with a frequency comparison circuit corresponding to the LC oscillation reference circuit (6). The frequency comparison circuit outputs the frequency comparison results of the two LC oscillation circuits (4) to the MCU.

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