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

Abstract

The present invention discloses an interference frequency band detection circuit, a control method thereof, and an air conditioner. The interference frequency band detection circuit is connected between a device under test and a main control unit, and includes a first low-pass filter circuit and a second low-pass filter circuit connected to the output end of the device under test, a first comparison circuit connected to the first low-pass filter circuit, and a second comparison circuit connected to the second low-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 based on the output signals of the first comparison circuit and the second comparison circuit. Compared with the existing technology, 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 capability of the device under test.

Description

Technical Field

[0001] The present 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] Currently, color-screen wired controllers and centralized controllers for air conditioners all utilize LCD touchscreens. These touchscreens are typically based on Compact Discrete Transceiver (CTP), which transmits data to the MCU via I2C communication. In high-interference environments, this interference can affect the touchscreen scanning frequency, thereby affecting the scanned data. This can lead to insensitivity and false triggering, impacting product performance. The traditional solution is to add filtering components, but these also attenuate normal communication data. Furthermore, the interference frequency bands vary across different operating environments, making it difficult to effectively address these diverse 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 existing technology, the filtering components 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 deal with the problems in various usage environments. The present invention proposes an interference frequency band detection circuit, a control method thereof, 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, and includes a first low-pass filter circuit and a second low-pass filter circuit connected to the output end of the device under test, a first comparison circuit connected to the first low-pass filter circuit, and a second comparison circuit connected to the second low-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 based on the output signals of the first comparison circuit and the second comparison circuit.

[0006] Furthermore, the first low-pass filter circuit includes: a capacitor C1, a capacitor C2, and an inductor L1;

[0007] One end of the inductor L1 is connected to the output end of the device under test as the input end of the first low-pass filter circuit, and the other end is connected to the input end of the second low-pass filter circuit as the output end of the first low-pass filter circuit. One end of the capacitor C1 is connected between the inductor L1 and the output end of the device under test, and the other end is grounded. One end of the capacitor C2 is connected between the inductor L1 and the input end of the second low-pass filter circuit, and the other end is grounded.

[0008] Furthermore, the second low-pass filter circuit includes: a capacitor C3, a capacitor C4, and an inductor L2;

[0009] One end of the inductor L2 is connected to the output end of the first low-pass filter circuit as the input end of the second low-pass filter circuit, and the other end is connected to the second comparison circuit as the output end of the second low-pass filter circuit. One end of the capacitor C3 is connected between the inductor L2 and the output end of the first low-pass filter circuit, and the other end is grounded. One end of the capacitor C4 is connected between the inductor L2 and the second comparison circuit, and the other end is grounded.

[0010] Furthermore, the first comparison circuit includes: a capacitor C5, a comparator U1;

[0011] The inverting input terminal of the comparator U1 is connected to the output terminal of the first low-pass filter circuit, the non-inverting input terminal is connected in series with the capacitor C5 and then receives the reference signal, and the output terminal is connected to the main control unit.

[0012] Furthermore, the second comparison circuit includes: a capacitor C5, a comparator U2;

[0013] The inverting input terminal of the comparator U2 is connected to the output terminal of the second low-pass filter circuit, the non-inverting input terminal is connected in series with the capacitor C5 and then receives the reference signal, and the output terminal is connected to the main control unit.

[0014] Furthermore, the cutoff frequency of the first low-pass filter circuit satisfies: L1 =f0+f B / 2;

[0015] Among them, f L1 is the cut-off frequency of the first low-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.

[0016] Furthermore, the capacitor C1 and the capacitor C2 satisfy: C1 = C2 = 1 / (2πZf L1 );

[0017] The inductor L1 satisfies: L1=Z / (2πf L1 );

[0018] Wherein C1 is the capacitance value of the capacitor C1, C2 is the capacitance value of the capacitor C2, L1 is the inductive reactance of the inductor L1, Z is the target impedance value of the interference frequency band detection circuit, f L1 is the cutoff frequency of the first low-pass filter circuit.

[0019] Furthermore, the cutoff frequency of the second low-pass filter circuit satisfies: L2=f0-f B / 2;

[0020] Among them, f L2 is the cut-off frequency of the second low-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.

[0021] Furthermore, the capacitor C3 and the capacitor C4 satisfy: C3 = C4 = 1 / (2πZf L2 );

[0022] The inductor L2 satisfies: L2=Z / (2πf L2 );

[0023] Wherein C3 is the capacitance value of the capacitor C3, C4 is the capacitance value of the capacitor C4, L2 is the inductive reactance of the inductor L2, Z is the target impedance value of the interference frequency band detection circuit, f L2 is the cutoff frequency of the second low-pass filter circuit.

[0024] Furthermore, the cutoff frequency of the first low-pass filtering circuit is higher than the cutoff frequency of the second low-pass filtering circuit.

[0025] The present invention also proposes a control method for an interference frequency band detection circuit, comprising:

[0026] Setting an initial scanning frequency of the device under test by the main control unit, and outputting a reference signal to the first comparison circuit and the second comparison circuit according to the initial scanning frequency;

[0027] determining an interference frequency band of the device under test according to output signals outputted to the main control unit by the first comparison circuit and the second comparison circuit;

[0028] Adjusting a target scanning frequency of the device under test according to an interference frequency band of the device under test;

[0029] The main control unit starts scanning the device under test and re-executes the detection action.

[0030] 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:

[0031] 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;

[0032] 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 first preset interval;

[0033] 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.

[0034] Furthermore, the first preset interval is an interval where the interference frequency band is lower than the cutoff frequency of the second low-pass filter circuit;

[0035] The second preset interval is an interval where the interference frequency band is between the cutoff frequency of the first low-pass filter circuit and the cutoff frequency of the second low-pass filter circuit;

[0036] The third preset interval is an interval in which the interference frequency band is higher than the cutoff frequency of the first low-pass filtering circuit.

[0037] Further, the method includes adjusting a target scanning frequency of the device under test according to an interference frequency band of the device under test, including:

[0038] 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;

[0039] If the interference frequency band of the device under test is within the third preset range, adjusting the target scanning frequency of the device under test to be within the second preset range;

[0040] 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.

[0041] The present invention further provides an air conditioner, wherein the controller of the air conditioner includes a touch screen having the above-mentioned interference frequency band detection circuit.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] The present invention proposes 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

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0045] Figure 1 A circuit block diagram of the present invention as a whole;

[0046] Figure 2 This is the control logic diagram of the present invention as a whole;

[0047] Figure 3 It is a circuit principle diagram of the present invention;

[0048] Figure 4 This is a filtering frequency band diagram of the present invention. DETAILED DESCRIPTION

[0049] 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 with reference to 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.

[0050] Thus, a feature indicated in this specification is intended to illustrate one of the features of one embodiment of the present invention, rather than to imply that every embodiment of the present invention must have the described feature. In addition, it should be noted that this specification describes many features. Although certain features can be combined together to illustrate possible system designs, these features can also be used in other, not explicitly described, combinations. Thus, unless otherwise noted, the described combinations are not intended to be limiting.

[0051] The principle and structure of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0052] The traditional solution to signal interference during data transmission is to add filtering devices. However, these devices also attenuate normal communication data, and the interference frequency bands vary across different usage environments, making it difficult to effectively address various environments. The present invention proposes an interference frequency band detection circuit that detects the interference frequency band of the device under test and sets the scanning frequency within a low-interference frequency band, thereby improving the device's anti-interference capability.

[0053] 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 low-pass filter circuit and a second low-pass filter circuit connected to the output end of the device under test, a first comparison circuit connected to the first low-pass filter circuit, and a second comparison circuit connected to the second low-pass filter circuit. The main control unit is connected to the first comparison circuit and the second comparison circuit respectively.

[0054] Among them, the cutoff frequency of the first low-pass filter circuit is f L1 , only the interference frequency band is lower than the cutoff frequency f L1Only when it passes through the first low-pass filter circuit, the cut-off frequency of the second low-pass filter circuit is f L2 , only the interference frequency band is lower than the cutoff frequency f L2 Only when it passes through the second low-pass filtering circuit, the first comparison circuit and the second comparison circuit can be used to determine whether the interference frequency band passes through the first low-pass filtering circuit and the second low-pass filtering 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, and then control the scanning frequency to be in the low interference frequency range, thereby improving the anti-interference ability.

[0055] Specifically, when the first comparison circuit outputs a high level signal, it indicates that the interference frequency band is lower than the cutoff frequency f L1 When the second comparison circuit outputs a high-level signal, it indicates that the interference frequency band is lower than the cutoff frequency f L2 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 higher than the cut-off frequency f L1 ;

[0056] 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 cutoff frequency f L2 ;

[0057] The first comparison circuit and the second comparison circuit both output low-level signals. In this case, the interference frequency band is higher than the cutoff frequency f L1 .

[0058] It should be noted that the cutoff frequency f L2 Below the cutoff frequency f L1 Therefore, 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.

[0059] See Figure 3 , the first low-pass filter circuit includes: capacitor C1, capacitor C2, and inductor L1;

[0060] Among them, one end of the inductor L1 is connected to the output end of the device under test as the input end of the first low-pass filter circuit, and the other end is connected to the input end of the second low-pass filter circuit as the output end of the first low-pass filter circuit. One end of the capacitor C1 is connected between the inductor L1 and the output end of the device under test, and the other end is grounded. One end of the capacitor C2 is connected between the inductor L1 and the input end of the second low-pass filter circuit, and the other end is grounded.

[0061] The second low-pass filter circuit includes: capacitor C3, capacitor C4, and inductor L2;

[0062] Among them, one end of the inductor L2 is connected to the output end of the first low-pass filter circuit as the input end of the second low-pass filter circuit, and the other end is connected to the second comparison circuit as the output end of the second low-pass filter circuit. One end of the capacitor C3 is connected between the inductor L2 and the output end of the first low-pass filter circuit, and the other end is grounded. One end of the capacitor C4 is connected between the inductor L2 and the second comparison circuit, and the other end is grounded.

[0063] The first low-pass filter circuit and the second low-pass filter circuit are both third-order low-pass filter circuits, whose signals can pass only when the input frequency is lower than their cutoff frequency, and can be used to determine the interference frequency band of the device under test.

[0064] The first comparison circuit includes: a capacitor C5 and a comparator U1;

[0065] The inverting input terminal of the comparator U1 is connected to the output terminal of the first low-pass filter circuit, the non-inverting input terminal is connected in series with a capacitor C5 and then receives a reference signal, and the output terminal is connected to the main control unit.

[0066] The second comparison circuit includes: a capacitor C3 and a comparator U2;

[0067] The inverting input terminal of the comparator U2 is connected to the output terminal of the second low-pass filter circuit, the non-inverting input terminal is connected in series with a capacitor C5 and then receives a reference signal, and the output terminal is connected to the main control unit.

[0068] See 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 cutoff frequency f of the first low-pass filter circuit is 1 / 4. L1 Higher than the cutoff frequency f of the second low-pass filter circuit L2 When the communication signal has a frequency lower than the cutoff frequency f L2 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 L1 With the cutoff frequency fL2 When the communication signal has a frequency higher than the cutoff frequency f, SIG1 is a high level signal and SIG2 is a low level signal. L1 When the interference frequency band is in the interference frequency band, SIG1 and SIG2 are both low-level signals. The main control unit can determine the interference frequency band according to the status 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 by the device under test to the main control unit.

[0069] In the present invention, the device under test is a touch screen, and data is transmitted between its touch TP and 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.

[0070] See Figure 4 On the right is the attenuation characteristic of the signal after passing through the first low-pass filter circuit. There is a dotted line in the horizontal direction, which represents the cutoff line. It means that the frequency signals below this line are severely attenuated. It can be regarded as 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 low-pass filter circuit is only below the cutoff frequency f. L1 The signals that can pass through the second low-pass filter circuit are only those below the cut-off frequency f L2 signal.

[0071] In the present invention, according to the filtering characteristics of the first low-pass filter circuit and the second low-pass filter circuit, three frequency intervals are set, namely the first preset interval, in which the interference frequency band is lower than the cut-off frequency f L2 ;

[0072] The second preset interval, in which the interference frequency band is at the cutoff frequency f L1 With the cutoff frequency f L2 between;

[0073] The third preset interval, in which the interference frequency band is higher than the cutoff frequency f L1 .

[0074] 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 (the initial sweep frequency is prioritized);

[0075] If SIG1=1 and SIG2=0, it means that the low interference frequency is in the first preset interval, and the scanning frequency is set in the first preset interval;

[0076] 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.

[0077] 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 low-pass filter circuit in the present invention satisfies: f L1 =f0+f B / 2;

[0078] Among them, f L1 is the cutoff frequency of the first low-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.

[0079] The cutoff frequency of the second low-pass filter circuit satisfies: f L2 =f0-f B / 2;

[0080] Among them, f L2 is the cutoff frequency of the second low-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.

[0081] 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 low-pass filter circuit can be set to: f L1 =f0+f B / 2+d, the cutoff frequency of the second low-pass filter circuit can be set to f L2 =f0-f B / 2-d, where d is the margin set in actual application.

[0082] In order to match the cutoff frequency of the first low-pass filter circuit, the capacitor C1 and the capacitor C2 in the first low-pass filter circuit are set to satisfy: C1 = C2 = 1 / (2πZf L1 );

[0083] Inductor L1 satisfies: L1=Z / (2πf L1 );

[0084] Where C1 is the capacity of capacitor C1, C2 is the capacity of capacitor C2, L1 is the inductive reactance of inductor L1, Z is the target impedance value of the interference frequency band detection circuit, f L1 is the cutoff frequency of the first low-pass filter circuit.

[0085] To match the cutoff frequency of the second low-pass filter circuit, the capacitor C3 and the capacitor C4 in the second low-pass filter circuit are set to satisfy: C3=C4=1 / (2πZf L2 );

[0086] Inductor L2 satisfies: L2=Z / (2πf L2 );

[0087] Where C3 is the capacity of capacitor C3, C4 is the capacity of capacitor C4, L2 is the inductive reactance of inductor L2, f L2 is the cutoff frequency of the second low-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 50 ohms.

[0088] After the above settings, the cutoff frequencies of the first low-pass filter circuit and the second low-pass filter circuit can be set to meet the setting requirements of the interference frequency band detection circuit.

[0089] The present invention also proposes a control method for an interference frequency band detection circuit, which includes:

[0090] The main control unit sets an initial scanning frequency for the device under test, and outputs a reference signal to the first comparison circuit and the second comparison circuit according to the initial scanning frequency;

[0091] determining an interference frequency band of the device under test according to output signals outputted to the main control unit by the first comparison circuit and the second comparison circuit;

[0092] Adjust the target scanning frequency of the device under test according to the interference frequency band of the device under test;

[0093] The main control unit scans the device under test and re-executes the detection action.

[0094] The method of determining the interference frequency band of the device under test according to the output signals outputted to the main control unit by the first comparison circuit and the second comparison circuit includes:

[0095] 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;

[0096] 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 the first preset interval;

[0097] 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 range.

[0098] The first preset interval is an interval where the interference frequency band is lower than the cutoff frequency of the second low-pass filter circuit;

[0099] The second preset interval is an interval where the interference frequency band is between the cutoff frequency of the first low-pass filter circuit and the cutoff frequency of the second low-pass filter circuit;

[0100] The third preset interval is an interval where the interference frequency band is higher than the cutoff frequency of the first low-pass filter circuit.

[0101] 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 within the remaining intervals to improve the anti-interference capability. Therefore, in the present invention, adjusting the target scanning frequency of the device under test according to the interference frequency band of the device under test includes:

[0102] 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;

[0103] If the interference frequency band of the device under test is within the third preset range, adjusting the target scanning frequency of the device under test to be within the second preset range;

[0104] 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.

[0105] See Figure 2 The 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 judge 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.

[0106] The present invention also provides an air conditioner, wherein the controller of the air conditioner adopts a touch screen, and the touch screen has the above-mentioned interference frequency scanning circuit.

[0107] Specifically, the air conditioner controller 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.

[0108] Compared to existing technologies, the present invention proposes an interference frequency band detection circuit that 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 capability and service life of the device under test. Furthermore, the present invention can detect the interference frequency band and adaptively adjust the scanning frequency band to the low-interference frequency band, making it adaptable to various usage environments.

[0109] 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 scope of protection 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 low-pass filter circuit and a second low-pass filter circuit connected to the output end of the device under test, a first comparison circuit connected to the first low-pass filter circuit, and a second comparison circuit connected to the second low-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 low-interference frequency band of the device under test is in the third preset interval; When the first comparison circuit outputs a high-level signal and the second comparison circuit outputs a low-level signal, the low-interference frequency band of the device under test is in a first preset interval; When the first comparison circuit and the second comparison circuit both output low-level signals, the interference frequency band of the device under test is in a third preset interval.

2. The interference frequency band detection circuit according to claim 1, characterized in that: The first low-pass filter circuit includes: a capacitor C1, a capacitor C2, and an inductor L1; One end of the inductor L1 is connected to the output end of the device under test as the input end of the first low-pass filter circuit, and the other end is connected to the input end of the second low-pass filter circuit as the output end of the first low-pass filter circuit. One end of the capacitor C1 is connected between the inductor L1 and the output end of the device under test, and the other end is grounded. One end of the capacitor C2 is connected between the inductor L1 and the input end of the second low-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 low-pass filter circuit includes: a capacitor C3, a capacitor C4, and an inductor L2; One end of the inductor L2 is connected to the output end of the first low-pass filter circuit as the input end of the second low-pass filter circuit, and the other end is connected to the second comparison circuit as the output end of the second low-pass filter circuit. One end of the capacitor C3 is connected between the inductor L2 and the output end of the first low-pass filter circuit, and the other end is grounded. One end of the capacitor C4 is connected between the inductor L2 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 C5 and a comparator U1; The inverting input terminal of the comparator U1 is connected to the output terminal of the first low-pass filter circuit, the non-inverting input terminal is connected in series with the capacitor C5 and then receives the reference signal, and the output terminal is 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 C5 and a comparator U2; The inverting input terminal of the comparator U2 is connected to the output terminal of the second low-pass filter circuit, the non-inverting input terminal is connected in series with the capacitor C5 and then receives the reference signal, and the output terminal is 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 low-pass filter circuit satisfies: L1 =f0+f B / 2; Among them, f L1 is the cut-off frequency of the first low-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.

7. The interference frequency band detection circuit according to claim 2, characterized in that: The capacitor C1 and the capacitor C2 satisfy: C1 = C2 = 1 / (2πZf L1 ); The inductor L1 satisfies: L1=Z / (2πf L1 ); Wherein C1 is the capacitance value of the capacitor C1, C2 is the capacitance value of the capacitor C2, L1 is the inductive reactance of the inductor L1, Z is the target impedance value of the interference frequency band detection circuit, f L1 is the cutoff frequency of the first low-pass filter circuit.

8. The interference frequency band detection circuit according to claim 1, characterized in that: The cut-off frequency of the second low-pass filter circuit satisfies: L2 =f0-f B / 2; Among them, f L2 is the cut-off frequency of the second low-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 capacitor C3 and the capacitor C4 satisfy: C3 = C4 = 1 / (2πZf L2 ); The inductor L2 satisfies: L2=Z / (2πf L2 ); Wherein C3 is the capacitance value of the capacitor C3, C4 is the capacitance value of the capacitor C4, L2 is the inductive reactance of the inductor L2, Z is the target impedance value of the interference frequency band detection circuit, f L2 is the cutoff frequency of the second low-pass filter circuit.

10. The interference frequency band detection circuit according to claim 1, characterized in that: The cutoff frequency of the first low-pass filter circuit is higher than the cutoff frequency of the second low-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 an initial scanning frequency of the device under test by the main control unit, and outputting a reference signal to the first comparison circuit and the second comparison circuit according to the initial scanning frequency; determining an interference frequency band of the device under test according to output signals outputted to the main control unit by the first comparison circuit and the second comparison circuit; 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 first 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 lower than the cutoff frequency of the second low-pass filter circuit; The second preset interval is an interval in which the interference frequency band is between the cutoff frequency of the first low-pass filter circuit and the cutoff frequency of the second low-pass filter circuit; The third preset interval is an interval in which the interference frequency band is higher than the cutoff frequency of the first low-pass filtering 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 range, adjusting the target scanning frequency of the device under test to be within the second preset range; 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 includes a touch screen, characterized in that: The touch screen comprises the interference frequency band detection circuit according to any one of claims 1 to 10.

Images