Interference frequency band detection circuit and control method thereof, and air conditioner

Abstract

The present invention discloses an interference frequency band detection circuit and a control method thereof, and an air conditioner. The interference frequency band detection circuit includes: a first high-pass filter circuit and a second high-pass filter circuit connected to the output end of the device under test and a main control unit, a first comparison circuit connected to the first high-pass filter circuit, and a second comparison circuit connected to the second high-pass filter circuit. The main control unit is connected to the first comparison circuit and the second comparison circuit respectively, and can determine the interference frequency band of the device under test according to the output signals of the first comparison circuit and the second comparison circuit. Compared with the prior art, the present invention can determine the interference frequency band of the device under test, and adjust the scanning frequency to a low-interference frequency band, thereby improving the anti-interference ability of the device under test.

Description

Technical Field

[0001] The invention relates to the field of data communication, and in particular to an interference frequency band detection circuit and a control method thereof, and an air conditioner. Background Art

[0002] At present, color screen wire controllers and centralized controllers used in air conditioners all use LCD touch screens. The touch solution is generally based on CTP. The touch TP and MCU transmit data through I2C communication. When the environmental interference is large, the interference will affect the touch scanning frequency, thereby affecting the scanning data, resulting in insensitive touch, false triggering, etc., affecting the use of the product. The traditional solution is to add filtering devices, but filtering devices also have an attenuation effect on normal communication data, and the interference frequency bands are different in different usage environments, making it difficult to effectively cope with various usage environments.

[0003] Therefore, how to design an interference frequency band detection circuit and its control method, air conditioner, which can determine the interference frequency band and adjust the scanning frequency to the low interference frequency band to improve the anti-interference ability, is a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0004] In view of the prior art, the filter device also has an attenuation effect on normal communication data, and the interference frequency bands in different usage environments are different, making it difficult to effectively deal with the problems in various usage environments. The present invention proposes an interference frequency band detection circuit and its control method, and an air conditioner.

[0005] The technical solution of the present invention is to propose an interference frequency band detection circuit, which is connected between the device under test and the main control unit, including a first high-pass filter circuit and a second high-pass filter circuit connected to the output end of the device under test, a first comparison circuit connected to the first high-pass filter circuit, and a second comparison circuit connected to the second high-pass filter circuit. The main control unit is connected to the first comparison circuit and the second comparison circuit respectively, and can determine the interference frequency band of the device under test according to the output signals of the first comparison circuit and the second comparison circuit.

[0006] Further, the first high-pass filter circuit includes: an inductor L1, an inductor L2, and a capacitor C1;

[0007] One end of the capacitor C1 is connected to the output end of the device under test as the input end of the first high-pass filter circuit, and the other end is connected to the input end of the second high-pass filter circuit as the output end of the first high-pass filter circuit. One end of the inductor L1 is connected between the capacitor C1 and the output end of the device under test, and the other end is grounded. One end of the inductor L2 is connected between the capacitor C1 and the input end of the second high-pass filter circuit, and the other end is grounded.

[0008] Further, the second high-pass filter circuit includes: an inductor L3, an inductor L4, and a capacitor C2;

[0009] One end of the capacitor C2 is connected to the output end of the first high-pass filter circuit as the input end of the second high-pass filter circuit, and the other end is connected to the second comparison circuit as the output end of the second high-pass filter circuit. One end of the inductor L3 is connected between the capacitor C2 and the output end of the first high-pass filter circuit, and the other end is grounded. One end of the inductor L4 is connected between the capacitor C2 and the second comparison circuit, and the other end is grounded.

[0010] Further, the first comparison circuit includes: a capacitor C3, a comparator U1;

[0011] The non-inverting input terminal of the comparator U1 is connected to the output terminal of the first high-pass filter circuit, the reverse

[0012] The input end is connected in series with the capacitor C3 and then receives the reference signal, and the output end is connected to the main control unit.

[0013] Further, the second comparison circuit includes: a capacitor C3, a comparator U2;

[0014] The comparator U2 has a non-inverting input terminal connected to the output terminal of the second high-pass filter circuit, an inverting input terminal connected in series with the capacitor C3 and then connected to a reference signal, and an output terminal connected to the main control unit.

[0015] Furthermore, the cut-off frequency of the first high-pass filter circuit satisfies: H1 =f0-f B / 2;

[0016] Among them, f H1 is the cut-off frequency of the first high-pass filter circuit, f0 is the frequency of the main control unit to the waiting

[0017] Initial scanning frequency of the device under test, f B is the interference bandwidth of the device under test.

[0018] Furthermore, the inductance L1 and the inductance L2 satisfy: L1=L2=Z / (2 f H1 );

[0019] The capacitor C1 satisfies: C1=1 / (4 f H1 );

[0020] Wherein L1 is the inductive reactance of the inductor L1, L2 is the inductive reactance of the inductor L2, C1 is the capacitance of the capacitor C1, Z is the target impedance value of the interference frequency band detection circuit, f H1is the cut-off frequency of the first high-pass filter circuit.

[0021] Furthermore, the cut-off frequency of the second high-pass filter circuit satisfies: H2 =f0+f B / 2;

[0022] Among them, f H2 is the cut-off frequency of the second high-pass filter circuit, f0 is the frequency of the main control unit to the waiting

[0023] Initial scanning frequency of the device under test, f B is the interference bandwidth of the device under test.

[0024] Furthermore, the inductance L3 and the inductance L4 satisfy: L3=L4=Z / (2 f H2 );

[0025] The capacitor C2 satisfies: C2=1 / (4 f H2 );

[0026] Wherein L3 is the inductive reactance of the inductor L3, L4 is the inductive reactance of the inductor L4, C2 is the capacitance of the capacitor C2, Z is the target impedance value of the interference frequency band detection circuit, and f H2 is the cut-off frequency of the second high-pass filter circuit.

[0027] Furthermore, a cut-off frequency of the first high-pass filter circuit is smaller than a cut-off frequency of the second high-pass filter circuit.

[0028] The present invention also proposes a control method for an interference frequency band detection circuit, comprising:

[0029] The main control unit sets an initial scanning frequency for the device under test, and sends a scan to the device under test according to the initial scanning frequency.

[0030] The first comparison circuit and the second comparison circuit output reference signals;

[0031] Determine the interference frequency band of the device under test according to the output signals output by the first comparison circuit and the second comparison circuit to the main control unit;

[0032] Adjusting a target scanning frequency of the device under test according to an interference frequency band of the device under test;

[0033] The main control unit scans the device under test and re-executes the detection action.

[0034] Further, determining the interference frequency band of the device under test according to the output signals output by the first comparison circuit and the second comparison circuit to the main control unit includes:

[0035] If both the first comparison circuit and the second comparison circuit output high level signals, it is determined that

[0036] The low interference frequency band of the device under test is in a third preset interval;

[0037] If the first comparison circuit outputs a high level signal and the second comparison circuit outputs a low level signal, it is determined that the low interference frequency band of the device under test is in a third preset interval;

[0038] If both the first comparison circuit and the second comparison circuit output low level signals, it is determined that the interference frequency band of the device under test is in a third preset interval.

[0039] Furthermore, the first preset interval is an interval in which the interference frequency band is higher than the cutoff frequency of the second high-pass filter circuit;

[0040] The second preset interval is the interval between the cutoff frequency of the first high-pass filter circuit and the interference frequency band.

[0041] The interval between the cut-off frequencies of the second high-pass filter circuit;

[0042] The third preset interval is an interval where the interference frequency band is lower than the cutoff frequency of the first high-pass filter circuit.

[0043] Further, it includes: adjusting the target scanning frequency of the device under test according to the interference frequency band of the device under test, including:

[0044] If the low interference frequency band of the device under test is within a first preset interval, adjusting the target scanning frequency of the device under test to be within the first preset interval;

[0045] If the interference frequency band of the device under test is within the third preset interval, adjusting the target scanning frequency of the device under test to be within the second preset interval;

[0046] If the low interference frequency band of the device under test is within a third preset interval, the target scanning frequency of the device under test is adjusted to be within the third preset interval.

[0047] The present invention further provides an air conditioner, wherein a controller of the air conditioner has a touch screen, and the touch screen has the above-mentioned interference frequency band detection circuit.

[0048] Compared with the prior art, the present invention has at least the following beneficial effects:

[0049] The present invention provides an interference frequency band detection circuit, which can detect the interference frequency band and low-interference frequency band of a device under test and adjust the scanning frequency to the low-interference frequency band, thereby improving the anti-interference ability and service life of the device under test. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0051] Figure 1 A circuit block diagram of the present invention as a whole;

[0052] Figure 2 It is the control logic diagram of the whole invention;

[0053] Figure 3 is a circuit schematic diagram of the present invention;

[0054] Figure 4 This is a filtering frequency band diagram of the present invention. DETAILED DESCRIPTION

[0055] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0056] Thus, a feature indicated in this specification will be used to illustrate one of the features of an embodiment of the present invention, rather than implying that each embodiment of the present invention must have the described feature. In addition, it should be noted that this specification describes many features. Although some features can be combined together to illustrate possible system designs, these features can also be used in other combinations that are not explicitly described. Thus, unless otherwise stated, the described combinations are not intended to be limiting.

[0057] The principle and structure of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0058] The traditional solution to signal interference during data transmission is to add filtering devices, but filtering devices also have an attenuation effect on normal communication data, and the interference frequency bands in different usage environments are different, making it difficult to effectively cope with various usage environments. The idea of ​​the present invention is to propose an interference frequency band detection circuit for detecting the interference frequency band of the device under test and setting the scanning frequency in a low interference frequency band, thereby improving the anti-interference ability of the device under test.

[0059] The interference frequency band detection circuit proposed in the present invention is connected between the device under test and the main control unit, and includes a first high-pass filter circuit and a second high-pass filter circuit connected to the output end of the device under test, a first comparison circuit connected to the first high-pass filter circuit, and a second comparison circuit connected to the second high-pass filter circuit, and the main control unit is respectively connected to the first comparison circuit and the second comparison circuit.

[0060] Among them, the cut-off frequency of the first high-pass filter circuit is f H1 , only the interference frequency band is higher than the cut-off frequency f H1 When the signal is 100 Hz, it can pass through the first high-pass filter circuit. The cut-off frequency of the second high-pass filter circuit is f H2 , only the interference frequency band is higher than the cut-off frequency f H2 Only when the interference frequency band passes through the second high-pass filter circuit, the first comparison circuit and the second comparison circuit can be used to determine whether the interference frequency band passes through the first high-pass filter circuit and the second high-pass filter circuit, so as to determine the frequency range in which the interference frequency band is located. The main control unit is connected to the output ends of the first comparison circuit and the second comparison circuit, and can determine the frequency range in which the interference frequency band is located according to the output signals of the first comparison circuit and the second comparison circuit, thereby controlling the scanning frequency to be in the low interference frequency range and improving the anti-interference ability.

[0061] Specifically, when the first comparison circuit outputs a high level signal, it indicates that the interference frequency band is higher than the cut-off frequency f H1 When the second comparison circuit outputs a high level signal, it indicates that the interference frequency band is higher than the cut-off frequency f H2 According to the different interference frequency bands, the first comparison circuit and the second comparison circuit can output three different level combinations, namely, the first comparison circuit and the second comparison circuit both output high level signals, in which case the low interference frequency band is lower than the cut-off frequency f H1 ;

[0062] The first comparison circuit outputs a high level signal, and the second comparison circuit outputs a low level signal. In this case, the low interference frequency band is lower than the cut-off frequency f H1 ;

[0063] The first comparison circuit and the second comparison circuit both output low-level signals. In this case, the interference frequency band is less than the cut-off frequency f H1 .

[0064] It should be noted that the cut-off frequency f H2 Above the cut-off frequency f H1Therefore, when the second comparison circuit outputs a high-level signal, the first comparison circuit must output a high-level signal. There is no situation where the first comparison circuit outputs a low-level signal and the second comparison circuit outputs a high-level signal. Therefore, there are only three level combinations in the present invention. The main control unit can determine the size of the interference frequency band according to different level combinations, thereby adjusting the scanning frequency to the low-interference frequency band, thereby improving the anti-interference ability of the device under test.

[0065] See also Figure 3 , the first high-pass filter circuit includes: an inductor L1, an inductor L2, and a capacitor C1;

[0066] Among them, one end of the capacitor C1 is connected to the output end of the device under test as the input end of the first high-pass filter circuit, and the other end is connected to the input end of the second high-pass filter circuit as the output end of the first high-pass filter circuit. One end of the inductor L1 is connected between the capacitor C1 and the output end of the device under test, and the other end is grounded. One end of the inductor L2 is connected between the capacitor C1 and the input end of the second high-pass filter circuit, and the other end is grounded.

[0067] The second high-pass filter circuit includes: an inductor L3, an inductor L4, and a capacitor C2;

[0068] Among them, one end of the capacitor C2 is connected to the output end of the first high-pass filter circuit as the input end of the second high-pass filter circuit, and the other end is connected to the second comparison circuit as the output end of the second high-pass filter circuit. One end of the inductor L3 is connected between the capacitor C2 and the output end of the first high-pass filter circuit, and the other end is grounded. One end of the inductor L4 is connected between the capacitor C2 and the second comparison circuit, and the other end is grounded.

[0069] Among them, the first high-pass filter circuit and the second high-pass filter circuit are both third-order high-pass filter circuits, and their signals can pass only when the input frequency is higher than their cut-off frequency, and can be used to determine the interference frequency band of the device under test.

[0070] The first comparison circuit includes: a capacitor C3 and a comparator U1;

[0071] The in-phase input terminal of the comparator U1 is connected to the output terminal of the first high-pass filter circuit, the inverting input terminal is connected in series with a capacitor C3 and then connected to a reference signal, and the output terminal is connected to the main control unit.

[0072] The second comparison circuit includes: a capacitor C3 and a comparator U2;

[0073] The in-phase input terminal of the comparator U2 is connected to the output terminal of the second high-pass filter circuit, the inverting input terminal is connected in series with a capacitor C3 and then connected to the reference signal, and the output terminal is connected to the main control unit.

[0074] See also Figure 1 and Figure 3, CLK is the communication signal sent by the device under test received by the main control unit at the current scanning frequency, CLKbase is the reference signal corresponding to the current scanning frequency, SIG1 and SIG2 are the output signals of the first comparison circuit and the second comparison circuit to the main control unit respectively, and the cut-off frequency f of the first high-pass filter circuit is H1 Less than the cut-off frequency f of the second high-pass filter circuit H2 When the communication signal has a frequency higher than the cutoff frequency f H2 When the interference frequency band in the communication signal is at the cutoff frequency f, SIG1 and SIG2 are both high-level signals; when the interference frequency band in the communication signal is at the cutoff frequency f H1 With the cut-off frequency f H2 When the communication signal has a frequency lower than the cutoff frequency f, SIG1 is a high level signal and SIG2 is a low level signal. H1 When the interference frequency band is reached, SIG1 and SIG2 are both low-level signals. The main control unit can determine the interference frequency band according to the states of the received output signals SIG1 and SIG2, and then determine the scanning frequency to be within the low-interference frequency band. It should be pointed out that after determining the interference frequency band, the remaining frequency bands are all low-interference frequency bands. Setting the scanning frequency of the device under test by the main control unit to the low-interference frequency band can avoid receiving interference signals to a great extent, thereby improving the anti-interference ability of the device under test. Among them, the interference frequency band of the device under test in the present invention refers to the frequency band of the interference signal in the signal transmitted from the device under test to the main control unit.

[0075] In the present invention, the device to be tested is a touch screen, and data is transmitted between the touch TP and the MCU (main control unit) through the I2C communication method. When the environmental interference is large, the interference frequency will affect the touch scanning frequency. After determining the interference frequency band in the present invention, the scanning frequency can be set to avoid the interference frequency band so that the scanning frequency is in a low interference range, which can minimize the impact of the interference frequency on the touch scanning frequency, thereby improving the anti-interference ability of the touch screen.

[0076] See also Figure 4 , the left side is the attenuation characteristic of the signal after the first high-pass filter circuit. There is a dotted line in the horizontal direction, which represents the cutoff line, which means that the frequency signals below this line are severely attenuated. It can be equivalent to filtering out these frequency signals. The frequency corresponding to the intersection of the cutoff line and the attenuation characteristic line is the cutoff frequency. Therefore, the signal that can pass through the first high-pass filter circuit is only higher than the cutoff frequency f H1 The signals that can pass through the second high-pass filter circuit are only those above the cut-off frequency f H2 signal.

[0077] In the present invention, according to the filtering characteristics of the first high-pass filtering circuit and the second high-pass filtering circuit, three frequency intervals are set, namely, the first preset interval, in which the interference frequency band is higher than the cut-off frequency fH2 ;

[0078] The second preset interval, in which the interference frequency band is at the cutoff frequency f H1 With the cut-off frequency f H2 between;

[0079] The third preset interval, in which the interference frequency band is less than the cut-off frequency f H1 .

[0080] Wherein, the high level signal is set to 1 and the low level signal is set to 0. If SIG1=0 and SIG2=0, it means that the interference frequency band is in the third preset interval, and the sweep frequency is set to the second preset interval (low frequency is prioritized).

[0081] If SIG1=1, SIG2=0, it means that the low interference frequency is in the third preset interval, and the scanning frequency is set in the third preset interval;

[0082] If SIG1=1 and SIG2=1, it means that the low interference frequency is in the third preset interval, and the scanning frequency is set in the third preset interval.

[0083] Furthermore, to ensure the validity of the selected frequency band, the width of each preset interval must be greater than the interference bandwidth. Here, only the second preset interval needs to be considered. Specifically, the cutoff frequency of the first high-pass filter circuit in the present invention satisfies: f H1 =f0-f B / 2;

[0084] Among them, f H1 is the cut-off frequency of the first high-pass filter circuit, f0 is the initial frequency of the device under test by the main control unit

[0085] Scanning frequency, f B is the interference bandwidth of the device under test.

[0086] The cut-off frequency of the second high-pass filter circuit satisfies: f H2 =f0+f B / 2;

[0087] Among them, f H2 is the cut-off frequency of the second high-pass filter circuit, f0 is the initial scanning frequency of the device under test by the main control unit, and f B is the interference bandwidth of the device under test.

[0088] The interference bandwidth can be obtained through actual testing, and a certain margin needs to be added when setting to ensure the effectiveness of the selected frequency band. In practice, the cutoff frequency of the first high-pass filter circuit can be set to: f H1 =f0-f B / 2-d, the cutoff frequency of the second high-pass filter circuit can be set to fH2 =f0+f B / 2+d, where d is the margin set in the actual application.

[0089] To match the cutoff frequency of the first high-pass filter circuit, the inductor L1 and the inductor L2 in the first high-pass filter circuit are set to satisfy: L1=L2=Z / (2 f H1 );

[0090] Capacitor C1 satisfies: C1=1 / (4 f H1 );

[0091] Where L1 is the inductive reactance of inductor L1, L2 is the inductive reactance of inductor L2, C1 is the capacitance of capacitor C1, Z is the target impedance value of the interference frequency band detection circuit, f H1 is the cut-off frequency of the first high-pass filter circuit.

[0092] To match the cutoff frequency of the second high-pass filter circuit, the inductor L3 and the inductor L4 in the second high-pass filter circuit are set to satisfy: L3=L4=Z / (2 f H2 );

[0093] Capacitor C2 satisfies: C2=1 / (4 f H2 );

[0094] Where L3 is the inductive reactance of inductor L3, L4 is the inductive reactance of inductor L4, C2 is the capacitance of capacitor C2, f H2 is the cut-off frequency of the second high-pass filter circuit, and Z is the target impedance value of the interference frequency band detection circuit, which can be set according to the actual circuit application and can generally be set to 50ohm.

[0095] Through the above settings, the cutoff frequencies of the first high-pass filter circuit and the second high-pass filter circuit can be set to meet the setting requirements of the interference frequency band detection circuit.

[0096] The present invention also proposes a control method for an interference frequency band detection circuit, which comprises:

[0097] The main control unit sets the initial scanning frequency of the device under test, and sends a signal to the first comparison unit according to the initial scanning frequency.

[0098] The circuit and the second comparison circuit output a reference signal;

[0099] Determine the interference frequency band of the device under test according to the output signal output by the first comparison circuit and the second comparison circuit to the main control unit;

[0100] Adjust the target scanning frequency of the device under test according to the interference frequency band of the device under test;

[0101] The main control unit scans the device under test and re-executes the detection action.

[0102] Wherein, determining the interference frequency band of the device under test according to the output signal outputted to the main control unit by the first comparison circuit and the second comparison circuit includes:

[0103] If both the first comparison circuit and the second comparison circuit output high level signals, the low level of the device under test is determined.

[0104] The interference frequency band is in the third preset interval;

[0105] If the first comparison circuit outputs a high level signal and the second comparison circuit outputs a low level signal, it is determined that the low interference frequency band of the device under test is in a third preset interval;

[0106] If both the first comparison circuit and the second comparison circuit output low level signals, it is determined that the interference frequency band of the device under test is in the third preset interval.

[0107] The first preset interval is an interval where the interference frequency band is higher than the cutoff frequency of the second high-pass filter circuit;

[0108] The second preset interval is an interval where the interference frequency band is between the cutoff frequency of the first high-pass filter circuit and the cutoff frequency of the second high-pass filter circuit;

[0109] The third preset interval is an interval where the interference frequency band is lower than the cut-off frequency of the first high-pass filter circuit.

[0110] After determining the preset interval where the interference frequency band is located, the remaining intervals can be determined as low-interference intervals, and the scanning frequency band can be set in the remaining intervals to improve the anti-interference ability. When determining the scanning frequency band, the low-frequency interval is given priority. Therefore, in the present invention, the target scanning frequency of the device under test is adjusted according to the interference frequency band of the device under test, including:

[0111] If the low interference frequency band of the device under test is within the first preset interval, adjusting the target scanning frequency of the device under test to be within the first preset interval;

[0112] If the interference frequency band of the device under test is within the third preset interval, adjusting the target scanning frequency of the device under test to be within the second preset interval;

[0113] If the low interference frequency band of the device under test is within the third preset interval, the target scanning frequency of the device under test is adjusted to be within the third preset interval.

[0114] See also Figure 2The overall control process of the present invention is to first determine the interference frequency band through the first comparison circuit and the second comparison circuit, and then determine whether the current scanning frequency is in the low interference frequency band. If so, it works normally, otherwise the scanning frequency is adjusted to the low interference frequency band.

[0115] The present invention also provides an air conditioner, the controller of which adopts a touch screen, and the touch screen has the above-mentioned interference frequency scanning circuit.

[0116] Specifically, the controller of the air conditioner includes a color screen wired controller, a centralized controller, etc., which has the above-mentioned touch screen. The touch solution is generally based on CTP. The touch TP and MCU transmit data through I2C communication, and the anti-interference ability is improved through the above-mentioned control method.

[0117] Compared with the prior art, the present invention proposes an interference frequency band detection circuit, which can detect the interference frequency band and low interference frequency band of the device under test, and adjust the scanning frequency to the low interference frequency band, thereby improving the anti-interference ability and service life of the device under test. In addition, the present invention can detect the interference frequency band and adaptively adjust the scanning frequency band to the interference frequency band, and can adapt to various use environments.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. Interference frequency band detection circuit, connected between the device under test and the main control unit, characterized in that: The device comprises a first high-pass filter circuit and a second high-pass filter circuit connected to the output end of the device under test, a first comparison circuit connected to the first high-pass filter circuit, and a second comparison circuit connected to the second high-pass filter circuit, wherein the main control unit is connected to the first comparison circuit and the second comparison circuit respectively, and can determine the interference frequency band of the device under test according to the output signals of the first comparison circuit and the second comparison circuit; The interference frequency band of the device under test has three preset intervals, and when the first comparison circuit and the second comparison circuit both output high-level signals, the interference frequency band is in the first preset interval; When the first comparison circuit outputs a high level signal and the second comparison circuit outputs a low level signal, the interference frequency band is in the second preset interval; When the first comparison circuit and the second comparison circuit both output low level signals, the interference frequency band is in the third preset interval.

2. The interference frequency band detection circuit according to claim 1, characterized in that: The first high-pass filter circuit includes: an inductor L1, an inductor L2, and a capacitor C1; One end of the capacitor C1 is connected to the output end of the device under test as the input end of the first high-pass filter circuit, and the other end is connected to the input end of the second high-pass filter circuit as the output end of the first high-pass filter circuit. One end of the inductor L1 is connected between the capacitor C1 and the output end of the device under test, and the other end is grounded. One end of the inductor L2 is connected between the capacitor C1 and the input end of the second high-pass filter circuit, and the other end is grounded.

3. The interference frequency band detection circuit according to claim 1, characterized in that: The second high-pass filter circuit includes: an inductor L3, an inductor L4, and a capacitor C2; One end of the capacitor C2 is connected to the output end of the first high-pass filter circuit as the input end of the second high-pass filter circuit, and the other end is connected to the second comparison circuit as the output end of the second high-pass filter circuit. One end of the inductor L3 is connected between the capacitor C2 and the output end of the first high-pass filter circuit, and the other end is grounded. One end of the inductor L4 is connected between the capacitor C2 and the second comparison circuit, and the other end is grounded.

4. The interference frequency band detection circuit according to claim 1, characterized in that: The first comparison circuit includes: a capacitor C3 and a comparator U1; The comparator U1 has a non-inverting input terminal connected to the output terminal of the first high-pass filter circuit, an inverting input terminal connected in series with the capacitor C3 and then connected to a reference signal, and an output terminal connected to the main control unit.

5. The interference frequency band detection circuit according to claim 1, characterized in that: The second comparison circuit includes: a capacitor C3 and a comparator U2; The comparator U2 has a non-inverting input terminal connected to the output terminal of the second high-pass filter circuit, an inverting input terminal connected in series with the capacitor C3 and then connected to a reference signal, and an output terminal connected to the main control unit.

6. The interference frequency band detection circuit according to claim 1, characterized in that: The cut-off frequency of the first high-pass filter circuit satisfies: H1 =f0-f B / 2; Among them, f H1 is the cut-off frequency of the first high-pass filter circuit, f0 is the frequency of the main control unit to the waiting Initial scanning frequency of the device under test, f B is the interference bandwidth of the device under test.

7. The interference frequency band detection circuit according to claim 2, characterized in that: The inductor L1 and the inductor L2 satisfy: L1=L2=Z / (2 f H1 ); The capacitor C1 satisfies: C1=1 / (4 f H1 ); Wherein L1 is the inductive reactance of the inductor L1, L2 is the inductive reactance of the inductor L2, C1 is the capacitance of the capacitor C1, Z is the target impedance value of the interference frequency band detection circuit, f H1 is the cut-off frequency of the first high-pass filter circuit.

8. The interference frequency band detection circuit according to claim 1, characterized in that: The cut-off frequency of the second high-pass filter circuit satisfies: H2 =f0+f B / 2; Among them, f H2 is the cut-off frequency of the second high-pass filter circuit, f0 is the initial scanning frequency of the main control unit for the device under test, and f B is the interference bandwidth of the device under test.

9. The interference frequency band detection circuit according to claim 3, characterized in that: The inductance L3 and the inductance L4 satisfy: L3=L4=Z / (2 f H2 ); The capacitor C2 satisfies: C2=1 / (4 f H2 ); Wherein L3 is the inductive reactance of the inductor L3, L4 is the inductive reactance of the inductor L4, C2 is the capacitance of the capacitor C2, Z is the target impedance value of the interference frequency band detection circuit, and f H2 is the cut-off frequency of the second high-pass filter circuit.

10. The interference frequency band detection circuit according to claim 1, characterized in that: A cut-off frequency of the first high-pass filter circuit is smaller than a cut-off frequency of the second high-pass filter circuit.

11. A control method using the interference frequency band detection circuit according to any one of claims 1 to 10, characterized in that: include: Setting the main control unit to have an initial scanning frequency for the device under test, and outputting a reference signal to the first comparison circuit and the second comparison circuit according to the initial scanning frequency; Determine the interference frequency band of the device under test according to the output signals output by the first comparison circuit and the second comparison circuit to the main control unit; Adjusting a target scanning frequency of the device under test according to an interference frequency band of the device under test; The main control unit starts scanning the device under test and re-executes the detection action.

12. The control method according to claim 11, characterized in that: Determining the interference frequency band of the device under test according to the output signals output by the first comparison circuit and the second comparison circuit to the main control unit includes: If both the first comparison circuit and the second comparison circuit output high level signals, it is determined that The low interference frequency band of the device under test is in a third preset interval; If the first comparison circuit outputs a high level signal and the second comparison circuit outputs a low level signal, it is determined that the low interference frequency band of the device under test is in a third preset interval; If both the first comparison circuit and the second comparison circuit output low level signals, it is determined that the interference frequency band of the device under test is in a third preset interval.

13. The control method according to claim 12, characterized in that: The first preset interval is an interval where the interference frequency band is higher than the cutoff frequency of the second high-pass filter circuit; The second preset interval is the interference frequency band between the cutoff frequency of the first high-pass filter circuit and the second high-pass filter circuit. The interval between the cut-off frequencies of the pass filter circuit; The third preset interval is an interval where the interference frequency band is lower than the cutoff frequency of the first high-pass filter circuit.

14. The control method according to claim 12, characterized in that: include: Adjusting a target scanning frequency of the device under test according to an interference frequency band of the device under test includes: If the low interference frequency band of the device under test is within a first preset interval, adjusting the target scanning frequency of the device under test to be within the first preset interval; If the interference frequency band of the device under test is within the third preset interval, adjusting the target scanning frequency of the device under test to be within the second preset interval; If the low interference frequency band of the device under test is within a third preset interval, the target scanning frequency of the device under test is adjusted to be within the third preset interval.

15. An air conditioner, wherein the controller of the air conditioner has a touch screen, characterized in that: The touch screen has the interference frequency band detection circuit as claimed in any one of claims 1 to 10.

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