Eddy current sensor

Abstract

The utility model relates to an eddy current sensor, which comprises a detection circuit, at least two transmitting coils and at least two stacked receiving coil groups, each transmitting coil is in one-to-one correspondence with each receiving coil group, and the transmitting coils are completely identical and are connected in series. Each receiving coil group comprises at least two receiving coils with different phases, the receiving coils with the same phase in different receiving coil groups are completely the same and are connected in series, and the projections of the receiving coil groups in the vertical direction are completely overlapped. The utility model has the advantages that at least two stacked receiving coil groups are arranged, so that the air gap value between an inductor and a PCB (Printed Circuit Board) can be effectively increased.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, and in particular to an eddy current sensor. Background Technology

[0002] Eddy current sensors typically include a detection circuit, a transmitting coil, and one or more receiving coils. The principle is that the detection circuit inputs a high-frequency AC signal to the transmitting coil to generate an alternating magnetic field. This alternating magnetic field induces a voltage in the receiving coil. When a metal target approaches the receiving coil, the induced voltage in the receiving coil changes, and this change allows for the detection of the metal object's position.

[0003] Existing sensors are limited by the principle of eddy currents, and the air gap between the sensing object and the PCB cannot be designed to be very large. Otherwise, the sensor will produce abnormal output waveforms because the potential difference it detects is too small. Summary of the Invention

[0004] This invention mainly solves the above-mentioned problems and provides an eddy current sensor that can increase the air gap value between the sensing object and the PCB.

[0005] The technical solution adopted by this utility model to solve its technical problem is an eddy current sensor, including a detection circuit, at least two transmitting coils and at least two sets of stacked receiving coil groups. Each transmitting coil corresponds one-to-one with each set of receiving coil groups. All transmitting coils are identical and connected in series. Each set of receiving coils includes at least two receiving coils with different phases. Receiving coils with the same phase in different sets of receiving coils are identical and connected in series. The projections of each set of receiving coils in the vertical direction completely overlap.

[0006] As a preferred embodiment of the above solution, the receiving coil group is disposed on different layers of PCB board.

[0007] As a preferred embodiment of the above scheme, the receiving coils in the same receiving coil group are connected by blind holes at predetermined intervals.

[0008] As a preferred embodiment of the above scheme, in the adjacent receiving coil groups, the first end of each receiving coil in the previous receiving coil group is connected to the second end of the corresponding receiving coil in the next receiving coil group through a via.

[0009] As a preferred embodiment of the above scheme, the receiving coil is a sine coil or a cosine coil.

[0010] As a preferred embodiment of the above scheme, the detection circuit includes a detection chip, the high-frequency AC output terminal of the detection chip is connected to a circuit composed of various transmitting coils connected in series, and the input terminal of the detection chip is connected to a circuit composed of corresponding receiving coils in different receiving coil groups connected in series.

[0011] As a preferred embodiment of the above scheme, at least one additional filtering circuit is provided between the input terminal of the detection chip and each of the series-connected receiving coils.

[0012] The advantages of this invention are: it has at least two stacked receiving coil groups, which can effectively increase the air gap value between the sensing object and the PCB. Attached Figure Description

[0013] Figure 1 This is a three-dimensional structural diagram of the transmitting coil and the receiving coil.

[0014] Figure 2 This is a top view of the transmitting and receiving coils.

[0015] Figure 3 This is a side view of the transmitting and receiving coils.

[0016] Figure 4 This is a magnified view of a portion of the transmitting and receiving coils.

[0017] Figure 5 This is the circuit schematic for the detection circuit.

[0018] 1-Transmitting coil 2-Receiving coil group 3-Upper coil group 4-Lower coil group 5-Blind hole 6-Through hole Detailed Implementation

[0019] The technical solution of this utility model will be further described below through embodiments and in conjunction with the accompanying drawings.

[0020] Example:

[0021] This embodiment discloses an eddy current sensor, including a detection circuit, at least two transmitting coils, and at least two stacked receiving coil groups. The receiving coil groups are disposed on different layers of a PCB board, and each receiving coil group includes at least two receiving coils with different phases. The receiving coils are either sine coils or cosine coils.

[0022] like Figures 1 to 3As shown, in this embodiment, there are two transmitting coils 1 and two sets of receiving coils 2. Each receiving coil set contains two receiving coils with a 90° phase difference. One receiving coil is a sine coil, and the other is a cosine coil. The transmitting coils are stacked, and the receiving coil sets are located within the transmitting coils 1. Each transmitting coil 1 corresponds one-to-one with each set of receiving coils 2. The upper transmitting coil 1 and the upper receiving coil set 2 form the upper coil set 3, and the lower transmitting coil 1 and the lower receiving coil set 2 form the lower coil set 4.

[0023] The corresponding coils in the upper coil group 3 and the lower coil group 4 are completely identical, and the projections of the two coil groups in the vertical direction completely overlap. Specifically, the transmitting coil in the upper coil group 3 is completely identical to the transmitting coil in the lower coil group 4, the sine coil in the upper coil group 3 is completely identical to the sine coil in the lower coil group 4, and the cosine coil in the upper coil group 3 is completely identical to the cosine coil in the lower coil group 4.

[0024] like Figure 4 As shown, the receiving coils in the same receiving coil group are connected through blind vias 5 at predetermined intervals. In this embodiment, the sine coil and cosine coil are connected through blind vias 5 every half cycle. In adjacent receiving coil groups, the first end of each receiving coil in the previous receiving coil group is connected to the second end of the corresponding receiving coil in the next receiving coil group through a via 6. This connection method ensures that the signals generated by the upper and lower receiving coil groups are highly consistent and do not interfere with each other. It also allows the detection circuit to receive the signal superimposed from the upper and lower receiving coils, thereby increasing the air gap value between the sensing object and the PCB.

[0025] like Figure 5 As shown, the detection circuit includes a detection chip U1. The high-frequency AC output terminal of the detection chip U1 is connected to a circuit formed by various transmitting coils connected in series. The input terminal of the detection chip U1 is connected to a circuit formed by corresponding receiving coils from different receiving coil groups connected in series. In this embodiment, the detection chip U1 is an IPS2550 chip. Two transmitting coils are connected in series between pins TX1 and TX2, two sine coils are connected in series between pins RX1 and RX3, and two cosine coils are connected in series between pins RX2 and RX4. Furthermore, because there are two layers of coil groups, the eddy current sensor is more susceptible to electric field interference. Therefore, compared to the existing detection current, at least one additional filtering circuit is needed at each input terminal of the detection chip U1. In this embodiment, the additional filtering circuit is an RC filtering circuit.

[0026] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific 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 eddy current sensor, characterized in that: It includes a detection circuit, at least two transmitting coils and at least two sets of stacked receiving coil groups, each transmitting coil corresponding to each set of receiving coil groups, all transmitting coils being identical and connected in series, each receiving coil group including at least two receiving coils with different phases, receiving coils with the same phase in different receiving coil groups being identical and connected in series, and the projections of each receiving coil group in the vertical direction completely overlapping.

2. The eddy current sensor according to claim 1, characterized in that: The receiving coil group is mounted on different layers of PCB board.

3. The eddy current sensor according to claim 1, characterized in that: The receiving coils in the same receiving coil group are connected by blind holes at predetermined intervals.

4. The eddy current sensor according to claim 1, characterized in that: In the adjacent receiving coil groups, the first end of each receiving coil in the previous receiving coil group is connected to the second end of the corresponding receiving coil in the next receiving coil group through a via.

5. The eddy current sensor according to claim 1, characterized in that: The receiving coil is a sine coil or a cosine coil.

6. The eddy current sensor according to claim 1, characterized in that: The detection circuit includes a detection chip. The high-frequency AC output terminal of the detection chip is connected to a circuit composed of various transmitting coils connected in series, and the input terminal of the detection chip is connected to a circuit composed of corresponding receiving coils from different receiving coil groups connected in series.

7. The eddy current sensor according to claim 6, characterized in that: At least one additional filtering circuit is provided between the input terminal of the detection chip and the receiving coil.

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