Capacitive angle sensor with single excitation mode

Abstract

The invention relates to a capacitive angle sensor with a single excitation mode. The capacitive angle sensor comprises a stator plate, a rotor plate and a signal processing plate, the stator plate comprises an excitation area and a receiving area; the excitation area and the receiving area are respectively arranged on two opposite sides of the stator plate; the signal processing board is connected with a receiving area and an excitation area on the stator board, a signal excitation module in the signal processing board is used for sending an excitation signal to the excitation area of the stator board, and a signal acquisition module in the signal processing board is used for receiving a signal of the receiving area of the stator board; and a signal demodulation module in the signal processing board is used for demodulating the received induction signal. Compared with a common capacitive angle sensor, the capacitive angle sensor with the single excitation mode makes full use of area resources of the stator plate and the rotor plate, so that the capacitive angle sensor is smaller in size and can be adapted to more use occasions.

Description

Technical Field

[0001] The invention relates to the technical field of electronic measurement, in particular to a capacitive grating angle sensor with a single excitation mode. Background Art

[0002] Angle sensors are devices used to detect angle changes.

[0003] Angle sensors are commonly divided into grating angle sensors, Hall angle sensors and capacitive grating angle sensors. Compared with grating angle sensors and Hall angle sensors, capacitive grating angle sensors have some basic advantages. However, due to the complex structure and large size of the capacitive grating angle sensors in the prior art, they are difficult to apply to different usage scenarios. Summary of the invention

[0004] The object of the present invention is to provide a capacitive angle sensor with a single excitation mode, which has a simple structure and a small volume and is easy to be miniaturized.

[0005] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] The present invention is composed of a stator plate, a rotor plate, and a signal processing plate; the stator plate is provided with an excitation area and a receiving area, and the excitation area and the receiving area are arranged on opposite sides of the stator plate; the excitation area is provided with a coarse excitation area and a fine excitation area; the receiving area is provided with a plurality of coarse receiving areas and fine receiving areas arranged along its radial direction; the coarse excitation area, the fine excitation area, the coarse receiving area, and the fine receiving area are all arranged in a fan ring shape; the coarse excitation area and the coarse receiving area are on the same circular ring on the stator plate, and the fine excitation area and the fine receiving area are arranged in a fan ring shape; The receiving areas are located on the same circular ring of the stator plate; the surface of the rotor plate is printed with a plurality of continuous repeating patterns, and the repeating patterns constitute a complete circumference of an electrode ring, including a coarse-divided induction annular area and a fine-divided induction annular area; the signal processing board is connected to the receiving area and the excitation area on the stator plate, the signal excitation module in the signal processing board is used to send an excitation signal to the excitation area of ​​the stator plate, the signal acquisition module in the signal processing board is used to receive the receiving area signal of the stator plate, and the signal demodulation module in the signal processing board is used to demodulate the received induction signal.

[0007] The present invention combines the excitation area and the receiving area in the stator plate into the same annular area, designs the excitation area to cover an integer multiple of the rotor plate pattern, leaves a distance of at least one pattern between the excitation area and the receiving area, and places the sensing pattern in the remaining annular band, thereby reducing the area of ​​a circular ring occupied by the excitation signal alone, making full use of the area resources of the stator plate and the rotor plate, making the angle sensor more compact and adaptable to more applicable occasions.

[0008] In one embodiment, the signal processing board, the stator plate and the rotor plate are coaxially arranged, the signal processing board and the stator plate are connected together through a signal hole, and the rotor plate is located directly below the stator plate.

[0009] In one embodiment, the coarse receiving area and the fine receiving area are formed with four consecutive receiving electrodes as a cycle.

[0010] In one of the embodiments, the signal excitation module uses a sine wave signal with a frequency higher than 7.2 kHz as an excitation signal, and the excitation signal is loaded into the coarse excitation area and the fine excitation area respectively.

[0011] In one embodiment, the repeating pattern is in the shape of a sine wave.

[0012] In one embodiment, the signal processing board, the stator plate and the rotor plate are all ring-shaped PCB boards. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of the stator plate;

[0014] Figure 2 is a schematic diagram of the rotor plate;

[0015] Figure 3 This is a schematic diagram of the signal processing board;

[0016] Explanation of the accompanying drawings: 10 - receiving area, 11 - subdivided receiving electrode, 12 - coarsely divided receiving electrode, 20 - excitation area, 21 - subdivided excitation area, 22 - coarsely divided excitation area, 30 - induction annular area, 31 - subdivided induction annular area, 32 - coarsely divided induction annular area, 40 - signal excitation module, 50 - signal acquisition module, 60 - signal demodulation module, 70 - microprocessor, 80 - communication module. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below in conjunction with the embodiments and with reference to the accompanying drawings.

[0018] The present invention is a single excitation mode capacitive grating angle sensor of a preferred embodiment, which is installed on the rotating shaft of a turntable. The single excitation mode capacitive grating angle sensor is composed of a stator plate, a rotor plate, and a signal processing board. The stator plate is provided with an excitation area 20 and a receiving area 10, the stator plate is connected to the signal processing board through a signal hole, the stator plate is coaxially arranged with the rotor plate and the signal processing board, the rotor plate is located directly below the stator plate, the stator plate and the rotor plate are both annular PCB boards, the rotor plate is coaxially installed with the rotating shaft of the turntable and rotates synchronously with the rotating shaft.

[0019] The excitation area 20 and the receiving area are located in the direction from the stator plate to the rotor plate, and the excitation area 20 and the receiving area 10 are separately arranged on opposite sides of the stator plate. Compared with the general capacitive grating angle sensor in which the excitation area and the sensing area are arranged on the same side of the circumference of the stator plate, the capacitive grating angle sensor in this embodiment has a streamlined ring width, so that the capacitive grating angle sensor is more compact and suitable for more usage occasions.

[0020] The receiving area 10 is provided with a plurality of coarse receiving electrodes 12 and fine receiving electrodes 11 arranged along its radial direction. The coarse receiving electrodes 12 and the fine receiving electrodes 11 are both arranged in a ring shape. The coarse receiving electrode 12 is close to the inner side of the circumference of the stator plate, and the fine receiving electrode 11 is close to the outer side of the circumference of the stator plate. The coarse receiving electrodes 12 and the fine receiving electrodes 11 form a cycle with an even number of receiving electrodes. In the present embodiment, the coarse receiving electrodes 12 and the fine receiving electrodes 11 form a cycle with every four consecutive receiving electrodes.

[0021] The excitation zone includes a coarse excitation zone 22 and a fine excitation zone 21. The coarse excitation zone 22 and the fine excitation zone 21 are both arranged in a ring shape. The coarse excitation zone 22 is close to the inner side of the circumference of the stator plate, and the fine excitation zone 21 is close to the outer side of the circumference of the stator plate.

[0022] The rotor plate can rotate synchronously with the turntable shaft, and a plurality of continuous repeating patterns are printed on its surface. The repeating patterns constitute a complete circumferential electrode ring, including a coarse-divided induction annular area 32 and a fine-divided induction annular area 31. The coarse-divided induction annular area 32 is close to the inner side of the circumference of the rotor plate, and the fine-divided induction annular area 31 is close to the outer side of the circumference of the rotor plate.

[0023] In this embodiment, a part of the induction annular area 30 is used as an induction pole between the rotor plates, and the other part is used as a reflection pole. The induction pole overlaps with the excitation area 20 on the stator plate, and capacitive coupling occurs. The induction pole is excited by the excitation area and generates an induced electrical signal. The reflection pole overlaps with the receiving area on the stator plate, and the receiving area receives the electrical signal of the reflection pole, that is, the modulation signal, and outputs the modulation signal for analysis.

[0024] The signal processing board in this embodiment includes a microprocessor 70, a signal excitation module 40, a signal acquisition module 50, a signal demodulation module 60 and a communication module 80. The signal excitation module 40 generates a sinusoidal wave excitation signal, which is loaded onto the coarse excitation area 22 and the fine excitation area 21. In this embodiment, the signal excitation module 40 uses a sinusoidal wave signal with a frequency higher than 7.2 kHz as the excitation signal.

[0025] The signal acquisition module 50 is connected to the sensing area on the stator plate to collect the modulated signal reflected from the reflector. In an embodiment, when the capacitive angle sensor in the single excitation mode is powered on, the microcontroller 70 controls the signal excitation module 40 to load the excitation signal to the excitation electrode. The signal acquisition module 50 collects the modulated signal of the coarse receiving area 12 and the fine receiving area 11. Since the amplitude of the modulated signal is weak, it needs to be amplified to increase the signal amplitude to hundreds of millivolts to thousands of millivolts. Therefore, the signal acquisition module contains an operational amplifier.

[0026] The signal demodulation module 60 is connected to the signal acquisition module 50. The signal demodulation module 60 receives eight groups of amplified modulated signals. After demodulation, the microcontroller can collect two groups of 16-bit data, one group is coarse angle data, and the other group is fine angle data. The absolute angle value is then obtained through calculation and finally output through the communication module 80.

Claims

1. A single excitation mode capacitive angle sensor, characterized in that: The invention comprises a stator circuit board, a rotor circuit board relative to the stator circuit board, and a processing circuit connected to the stator; the stator circuit board is provided with a fan-shaped pattern area, and the pattern area is divided into an excitation area and a receiving area, wherein the emission area is a unified single signal excitation area. The receiving area is divided into a coarse receiving area and a fine receiving area. The excitation area and the receiving area are arranged concentrically in the fan ring. The rotor is a sensing pattern area, which is divided into a coarse sensing annular area and a fine sensing annular area. The coarse sensing area and the fine sensing area are independent of each other and have no electrical connection. The sensing area is a plurality of continuous repeating patterns, each pattern corresponding to four continuous patterns in the receiving area of ​​the stator circuit board. The excitation area is an electrically conductive metal area, which is divided into two sector ring areas, and the center and center radius of each sector ring are respectively located at the same position as the center and radius of the sector ring of the corresponding receiving area; the receiving area is provided with a number of coarse electrodes and fine electrodes arranged along its radial direction; they correspond to the coarse receiving area and the fine receiving area respectively; the receiving area is a continuous plurality of repeated patterns, and the number of patterns is an integer multiple of 4; the number of patterns in the fine receiving area is more than the number of coarse divisions. The excitation area is a continuous sector ring segment area, which is respectively located on the circular ring area where the coarse receiving area and the fine receiving area are located. The excitation area, the coarse receiving area and the fine receiving area are all arranged in a sector ring shape. The sector ring length of the excitation area in the coarse-divided receiving area is an integer multiple of 4 times the length of a single coarse-divided pattern; the sector ring length of the excitation area in the fine-divided receiving area is an integer multiple of 4 times the length of a single fine-divided pattern. The processing circuit is connected to the signal excitation module and the signal receiving module respectively; the signal receiving module includes signal acquisition, amplification and filtering parts, and performs algorithm processing through the processor.

2. The single excitation mode capacitive angle sensor according to claim 1, characterized in that: The stator circuit board and the rotor circuit board are coaxially arranged.

3. The single excitation mode capacitive angle sensor according to claim 1, characterized in that: The number of the coarse-divided receiving electrodes and the number of the fine-divided receiving electrodes are both multiples of 4; and every 4 graphs constitute a measurement cycle.

4. The single excitation mode capacitive angle sensor according to claim 1, characterized in that: The excitation source adopts a single signal excitation and is coupled to the coarse image area and the fine graphic area at the same time.

5. The single excitation mode capacitive angle sensor according to claim 1, characterized in that: The stator circuit board and the rotor circuit board are both annular PCB boards.

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