Key detection circuit and electronic equipment
Through the combination of self-excitation oscillation circuit and detection circuit, sinusoidal oscillation signals with different frequencies are generated, which solves the problem that the button detection signal in radio frequency medical devices is disturbed by high-frequency energy, and realizes accurate button recognition and stable machine operation.
Patent Information
- Application Number
- CN202421896089.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-07
- Publication Date
- 2025-08-08
- Estimated Expiration
- 2034-08-07
AI Technical Summary
In radio frequency medical devices, the button detection signal is susceptible to interference from high-frequency energy signals, resulting in malfunctioning and misjudgment of the machine.
By setting up a self-excitation oscillation circuit to generate sinusoidal oscillation signals with different frequencies, using components such as transformers and transistors to generate oscillation signals with different frequencies from high-frequency energy signals, and convert them into DC voltage signals through the detection circuit for key recognition.
Effectively eliminate the impact of high-frequency energy signals on key detection signals, avoid machine misoperation and misjudgment, enhance the response speed and accuracy of the detection circuit, and simplify the circuit design.
Smart Images
Figure CN223205620U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of key detection circuits, and further to a key detection circuit and an electronic device. Background Art
[0002] In the application of RF medical devices, traditional universal button detection circuits face a significant problem. When button connection cables are routed alongside RF power lines, the button detection signal is susceptible to interference from the high-frequency energy signals transmitted by the power lines. This interference can cause the microcontroller to misbehave when identifying whether a button has been pressed, leading to malfunctions and misjudgments. Utility Model Content
[0003] In order to solve the above technical problems, the present application provides a key detection circuit and electronic equipment to effectively eliminate the influence of high-frequency energy signals on key detection signals, thereby avoiding malfunction and misjudgment of the machine.
[0004] In a first aspect, the present application provides a key detection circuit, comprising: a key circuit, comprising multiple key resistors and multiple key switches, wherein the multiple key resistors are respectively connected in series with the multiple key switches; a self-excited oscillation circuit, connected to the key circuit through the transformer; the key circuit is configured to connect a first key resistor to the self-excited oscillation circuit through the transformer, and the self-excited oscillation circuit is configured to adjust the amplitude of a sinusoidal oscillation signal based on the resistance value of the first key resistor, and the frequency of the sinusoidal oscillation signal is different from the frequency of an external high-frequency energy signal; a detection circuit, connected to the output end of the self-excited oscillation circuit, configured to determine a DC voltage signal based on the sinusoidal oscillation signal; a detection circuit, connected to the output end of the detection circuit, configured to determine the conduction state of the multiple key switches based on the DC voltage signal.
[0005] The above key detection circuit generates a sinusoidal oscillation signal of a certain frequency by setting the parameters of the self-oscillator circuit. The frequency of the sinusoidal oscillation signal is different from the frequency of the high-frequency energy signal. The sinusoidal oscillation signal is used as the key detection signal to identify key presses, effectively eliminating the influence of the high-frequency energy signal on the key detection signal, thus preventing the machine from malfunctioning and misjudging.
[0006] In one implementation, the self-excited oscillation circuit includes: a second resistor, a seventh resistor; a transistor, wherein the base of the transistor is connected to the external power supply through the second resistor, the emitter of the transistor is grounded through the seventh resistor, and the collector of the transistor is connected to the primary winding of the transformer; a third capacitor, wherein one end of the third capacitor is connected to the primary winding of the transformer and the other end is connected to the seventh resistor; and a fourth capacitor, wherein one end of the fourth capacitor is connected to the external power supply and the other end is connected to the seventh resistor.
[0007] The above key detection circuit, through the interaction of the transformer primary winding, transistor, seventh resistor, third capacitor, and fourth capacitor, continuously turns the transistor on and off. By adjusting the parameters of the transformer primary winding, third capacitor, and fourth capacitor, an oscillating signal with a frequency different from the high-frequency energy signal is generated and used as the key detection signal. This further eliminates the influence of the high-frequency energy signal on the key detection signal, preventing the device from malfunctioning or misjudging.
[0008] In one implementation, the self-oscillation circuit is configured to adjust the frequency of the sinusoidal oscillation signal based on parameters of the primary winding of the transformer, parameters of the third capacitor, and parameters of the fourth capacitor.
[0009] In one implementation, the detection circuit includes: a first diode and a seventh capacitor; one end of the seventh capacitor is connected to the primary winding of the transformer through the first diode, and the other end is grounded.
[0010] In one implementation, the detection circuit further includes: an eighth resistor and a potentiometer; one end of the eighth resistor is connected to the seventh capacitor, and the other end is grounded through the potentiometer.
[0011] The above-described key detection circuit detects the positive peak value of the sinusoidal oscillation signal through the first diode and the seventh capacitor, thereby enhancing the detection circuit's response speed and accuracy while simplifying the circuit design. The eighth resistor and potentiometer can be located inside or outside the detection circuit, achieving proportional reduction of the DC voltage to adapt it to the detection circuit's carrying capacity, thereby avoiding potential damage to the detection circuit and increasing the flexibility of the present application.
[0012] In one implementation, the detection circuit further includes: a second diode and a ninth resistor; one end of the ninth resistor is connected to the primary winding of the transformer, and the other end is connected to the anode of the second diode.
[0013] In one implementation, the detection circuit further includes: a sixth capacitor, and the sixth capacitor is connected to the potentiometer.
[0014] In one implementation, the self-excited oscillation circuit also includes: a first capacitor, a second capacitor and a fifth capacitor; one end of the second capacitor is connected to the base of the transistor, and the other end is connected to the first capacitor; one end of the fifth capacitor is connected to the primary winding of the transformer, and the other end is connected to the anode of the first diode.
[0015] In one implementation, the key circuit further includes: a first resistor and a sixth resistor, and the first resistor and the sixth resistor are both connected to the secondary winding of the transformer.
[0016] In a second aspect, the present application further provides an electronic device comprising any of the key detection circuits described above.
[0017] Compared with the prior art, the present invention has at least one of the following beneficial effects:
[0018] 1. By setting the parameters of the self-oscillation circuit, a sinusoidal oscillation signal of a certain frequency is generated. The frequency of the sinusoidal oscillation signal is different from the frequency of the high-frequency energy signal. The sinusoidal oscillation signal is used as the key detection signal for key recognition, thereby effectively eliminating the influence of the high-frequency energy signal on the key detection signal, avoiding malfunction and misjudgment of the machine.
[0019] 2. The transformer primary winding, transistor, seventh resistor, third capacitor, and fourth capacitor work together to continuously turn the transistor on and off. By adjusting the parameters of the transformer primary winding, third capacitor, and fourth capacitor, an oscillating signal with a frequency different from the high-frequency energy signal is generated. This oscillating signal serves as the key detection signal. This further eliminates the impact of the high-frequency energy signal on the key detection signal, preventing the device from malfunctioning or misjudging.
[0020] 3. By detecting the positive peak value of the sinusoidal oscillation signal through the first diode and the seventh capacitor, the response speed and accuracy of the detection circuit are enhanced, while simplifying the circuit design. The eighth resistor and potentiometer can be located inside or outside the detection circuit, achieving a proportional reduction in the DC voltage to adapt it to the carrying capacity of the detection circuit, thereby avoiding potential damage to the detection circuit and increasing the flexibility of the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The preferred embodiments will be described below in a clear and understandable manner with reference to the accompanying drawings to further illustrate the above-mentioned characteristics, technical features, advantages and implementation methods of the present invention.
[0022] Figure 1 A schematic structural diagram of a key detection circuit provided in an embodiment of the present application is shown;
[0023] Figure 2 A circuit diagram of a self-excited oscillation circuit provided in an embodiment of the present application is shown;
[0024] Figure 3 A circuit diagram of a key circuit provided in an embodiment of the present application is shown;
[0025] Figure 4 A circuit diagram of a detection circuit provided in an embodiment of the present application is shown. DETAILED DESCRIPTION
[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without inventive work.
[0027] To simplify the drawings, only the parts relevant to the utility model are schematically shown in each figure; they do not represent the actual structure of the product. Furthermore, to simplify the drawings and facilitate understanding, in some figures, only one of the components with the same structure or function is schematically depicted or labeled. In this document, "one" not only means "only one" but also "more than one."
[0028] It should be further understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.
[0029] It should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.
[0030] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.
[0031] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.
[0032] The key detection circuit uses resistors to divide the voltage to generate different voltages. The microcontroller (MCU) then identifies the key. When a key is pressed, the key detection circuit generates a fixed voltage through the resistor divider and sends it to the MCU's A / D port. The A / D value is then collected to determine which key was pressed.
[0033] In the application scenario of radio frequency medical devices, the key detection circuit faces a significant problem. When the key connection line and the radio frequency energy line are wired side by side, the key detection signal is easily interfered with by the high-frequency energy signal transmitted by the energy line. The present application proposes a key detection circuit, which generates an oscillation signal with a frequency different from that of the high-frequency energy signal through the cooperation of transistors and other components, and can achieve at least one of the following beneficial effects: effectively eliminating the influence of the high-frequency energy signal on the key detection signal, avoiding the machine's malfunction and misjudgment; or enhancing the response speed and accuracy of the detection circuit, while simplifying the circuit design.
[0034] Reference Attachment Figure 1 , which shows a structural diagram of a key detection circuit provided by an embodiment of the present application. Figure 1 As shown, it includes: a key circuit 100, a self-excited oscillation circuit 200, a detection circuit 300 and a detection circuit 400. The key circuit 100 includes multiple key resistors and multiple key switches, and the multiple key resistors are respectively connected in series with the multiple key switches. The self-excited oscillation circuit 200 is connected to the key circuit 100 through a transformer. The key circuit 100 is configured to connect the first key resistor to the self-excited oscillation circuit 200 through the transformer, and the self-excited oscillation circuit 200 is configured to adjust the amplitude of the sinusoidal oscillation signal based on the resistance value of the first key resistor, and the frequency of the sinusoidal oscillation signal is different from the frequency of the external high-frequency energy signal. The detection circuit 300 is connected to the output end of the self-excited oscillation circuit 200 and is configured to determine the DC voltage signal based on the sinusoidal oscillation signal. The detection circuit 400 is connected to the output end of the detection circuit 300 and is configured to determine the conduction state of the multiple key switches based on the DC voltage signal.
[0035] The self-excited oscillation circuit 200 can be an LC oscillation circuit, which is used to automatically generate a sinusoidal oscillation signal after power-on, and the frequency of the sinusoidal oscillation signal can be adjusted according to user needs, and the frequency of the sinusoidal oscillation signal is different from the frequency of the external high-frequency energy signal. When the key corresponding to the first key resistor is pressed, the first key resistor is connected to the self-excited oscillation circuit 200 through the transformer, so that the voltage induced by the primary winding of the transformer changes. Since the amplitude of the sinusoidal oscillation signal is determined by the voltage induced by the primary winding of the transformer, the amplitude of the sinusoidal oscillation signal will also change. Similarly, when other key resistors in the key circuit 100 are connected to the self-excited oscillation circuit 200 through the transformer, the amplitude of the sinusoidal oscillation signal will also change accordingly.
[0036] The detection circuit 300 receives a sinusoidal oscillation signal (also known as a key detection signal) and converts the sinusoidal oscillation signal from an AC voltage signal into a DC voltage signal. The DC voltage signal has the same amplitude as the sinusoidal oscillation signal, and the DC voltage signal is output to the detection circuit 400. The detection circuit 400 determines which keys are pressed and which keys are disconnected based on the voltage of the DC voltage signal, thereby executing the corresponding function. The detection circuit 400 can be an MCU, FPGA, or other device that identifies corresponding keys by voltage.
[0037] In the embodiments of the present application, the parameters of the self-oscillation circuit are set to generate a sinusoidal oscillation signal of a certain frequency, which is different from the frequency of the high-frequency energy signal. The sinusoidal oscillation signal is used as a key detection signal to identify key presses, thereby effectively eliminating the influence of the high-frequency energy signal on the key detection signal, thereby avoiding malfunctions and misjudgments of the machine.
[0038] Reference Attachment Figure 2 , which shows a circuit diagram of a self-excited oscillation circuit provided by an embodiment of the present application. Figure 2 As shown, it includes: a second resistor R2, a seventh resistor R7, a primary winding T1 of a transformer, a transistor Q1, a third capacitor C3, and a fourth capacitor C4 (the third capacitor C3 and the fourth capacitor C4 are essentially negative feedback resistors, used to control the rapid on / off of the transistor Q1). The primary winding T1 of the transformer is connected to the key circuit 100 and the detection circuit 300; the base of the transistor Q1 is connected to the external power supply via the second resistor R2 (the second resistor R2 is a current-limiting resistor for the base of the transistor Q1), the emitter of the transistor Q1 is grounded via the seventh resistor R7, and the collector of the transistor Q1 is connected to the primary winding T1 of the transformer; one end of the third capacitor C3 is connected to the primary winding T1 of the transformer, and the other end is connected to the seventh resistor R7; one end of the fourth capacitor C4 is connected to the external power supply, and the other end is connected to the seventh resistor R7.
[0039] After the self-excited oscillation circuit 200 is powered on, the voltage at the base of transistor Q1 gradually increases. When the voltage difference between the base voltage and the emitter voltage is greater than 0.7V, transistor Q1 is turned on. While transistor Q1 is turned on, the voltage across the seventh resistor R7 gradually increases. When the voltage across the seventh resistor R7 is greater than a preset value (the preset value may be 11.3V), transistor Q1 is turned off. Therefore, after power is applied, transistor Q1 is continuously turned on and off, thereby generating a sinusoidal oscillation signal. When the transistor is turned on, the waveform of the sinusoidal oscillation signal is positive, and when the transistor is turned off, the waveform of the sinusoidal oscillation signal is negative. The current flow direction when transistor Q1 is turned on and off is the same: external power supply (12V) - primary winding T1 of the transformer - transistor Q1 - seventh resistor R7 - ground.
[0040] The voltage across the transformer's primary winding T1 and secondary winding is directly proportional, and the current is inversely proportional. When the current in the transformer's primary winding T1 is constant, the current in the transformer's secondary winding is also constant. Therefore, the larger the key resistor inserted in series with the transformer's secondary winding, the greater the voltage across the transformer's secondary winding, and the greater the voltage induced across the transformer's primary winding T1.
[0041] Furthermore, the self-excited oscillation circuit 200 transmits the sinusoidal oscillation signal to the detection circuit 300. The detection circuit 300 converts the sinusoidal oscillation signal into a DC voltage signal and outputs the DC voltage signal to the detection circuit 400. The detection circuit 400 determines which keys are pressed and executes the corresponding function. The embodiment of the present application can also change the parameters of the primary winding T1, the third capacitor C3, and the fourth capacitor C4 of the transformer to change the frequency of the sinusoidal oscillation signal, so that the frequency of the oscillation signal is different from the frequency of the high-frequency energy signal.
[0042] In this embodiment, the transformer's primary winding, transistor, seventh resistor, third capacitor, and fourth capacitor interact to continuously turn the transistor on and off. By adjusting the parameters of the transformer's primary winding, third capacitor, and fourth capacitor, an oscillating signal with a frequency different from the high-frequency energy signal is generated, and this oscillating signal is used as the key detection signal. This effectively eliminates the influence of the high-frequency energy signal on the key detection signal, preventing the device from malfunctioning or misjudging.
[0043] Reference Attachment Figure 3 , which shows a circuit diagram of a key circuit provided by an embodiment of the present application. Figure 3 As shown, the system includes: a transformer secondary winding T2; multiple key resistors; and multiple key switches. The multiple key resistors are connected in series with the multiple key switches, and each key resistor is connected to the transformer secondary winding T2. When a user presses a key, the corresponding key switch responds, while the remaining key switches remain unresponsive. This causes the voltages of the transformer primary winding T1 and the transformer secondary winding T2 to change, causing the amplitude of the sinusoidal oscillation signal to change.
[0044] In some embodiments of the present application, when the number of the multiple key switches is 3, the corresponding key switches are respectively the first key switch SW1, the second key switch SW2 and the third key switch SW3, and the corresponding key resistors are respectively the third resistor R3, the fourth resistor R4 and the fifth resistor R5.
[0045] For example, when the user presses the button corresponding to the first push button switch SW1, the first push button switch SW1 is closed, and the third push button resistor R3 is connected in series with the secondary winding T2 of the transformer. At this time, the amplitude of the self-oscillation signal is determined by the third push button resistor R3. When the user switches from the button corresponding to the first push button switch SW1 to the button corresponding to the second push button switch SW2, the fourth push button resistor R4 is connected in series with the secondary winding T2 of the transformer. Since the fourth push button resistor R4 is greater than the third push button resistor R3, the amplitude of the self-oscillation signal will also increase accordingly. Furthermore, the DC voltage signals output by the detection circuit 300 to the detection circuit 400 twice are also different. The detection circuit 400 can determine that the user pressed the button corresponding to the first push button switch SW1 and the button corresponding to the second push button switch SW2 based on the two different DC voltage signals. In the embodiment of the present application, the number of multiple push button switches and multiple push button resistors is not limited and can be set according to user needs.
[0046] In some embodiments of the present application, the key circuit 100 further includes a first resistor R1 and a sixth resistor R6 to prevent a short circuit in the key circuit 100. If the key resistances are both greater than 0, the first resistor R1 and the sixth resistor R6 may not be provided.
[0047] Reference Attachment Figure 4 , which shows a circuit diagram of a detection circuit provided by an embodiment of the present application. Figure 4 As shown, the circuit includes: a first diode D1, a seventh capacitor C7, an eighth resistor R8, and a potentiometer RV1. The seventh capacitor C7 has one end connected to the primary winding T1 of the transformer via the first diode D1, and the other end grounded. The eighth resistor R8 has one end connected to the seventh capacitor C7, and the other end grounded via the potentiometer RV1.
[0048] The detection circuit 300 may be a diode detection circuit. After receiving a sinusoidal oscillation signal, the detection circuit 300 utilizes the unidirectional conduction characteristic of the first diode D1 (i.e., positive voltage conduction and negative voltage cutoff) to convert the sinusoidal oscillation signal into a DC voltage signal, which is then transmitted to the seventh capacitor C7 for energy storage. Because the voltage of the DC voltage signal may exceed the carrying capacity of the detection circuit 400, the voltage of the DC voltage signal is proportionally scaled down by the combined action of the eighth resistor R8 and the potentiometer RV1. The scaled-down DC voltage signal is then output to the detection circuit 400. The current from the conversion of the sinusoidal oscillation signal to the DC voltage flows from the first diode D1 to the seventh capacitor C7 to the eighth resistor R8 to the potentiometer RV1 to ground. The detection circuit 400 then proportionally amplifies the voltage of the scaled-down DC voltage signal, determines which button is pressed, and executes the corresponding function. Furthermore, the eighth resistor R8 and the potentiometer RV1 do not need to be internal to the detection circuit 300; they can be external devices that scale down the voltage of the DC voltage signal.
[0049] In the embodiments of the present application, the positive peak value of the sinusoidal oscillation signal is detected by the first diode and the seventh capacitor, thereby enhancing the response speed and accuracy of the detection circuit and simplifying the circuit design. The eighth resistor and potentiometer can be located inside or outside the detection circuit to achieve proportional reduction of the DC voltage signal voltage to adapt it to the load capacity of the detection circuit, thereby avoiding potential damage to the detection circuit and increasing the flexibility of the present application.
[0050] In some embodiments of the present application, the detection circuit 300 further includes a second diode D2, a ninth resistor R9, and a sixth capacitor C6. The ninth resistor R9 has one end connected to the primary winding T1 of the transformer and the other end connected to the anode of the second diode D2. The sixth capacitor C6 is connected to the potentiometer RV1.
[0051] In this application, the second diode D2 and the ninth resistor R9 are used to consume the negative voltage of the sinusoidal oscillation signal, and the current flows from the ninth resistor R9 to the anode of the second diode D2. The sixth capacitor C6 is a filter capacitor for filtering the proportionally scaled voltage.
[0052] In some embodiments of the present application, the self-excited oscillation circuit 200 further includes: a first capacitor C1, a second capacitor C2, and a fifth capacitor C5; one end of the second capacitor C2 is connected to the base of the transistor Q1, and the other end is connected to the first capacitor C1; one end of the fifth capacitor C5 is connected to the primary winding T1 of the transformer, and the other end is connected to the anode of the first diode D1.
[0053] An embodiment of the present application further provides an electronic device, comprising the key detection circuit described in any of the above embodiments.
[0054] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred embodiments of the present invention. It should be pointed out that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention, and such improvements and modifications should also be considered as the scope of protection of the present invention.
Claims
1. A key detection circuit, characterized in that: include: A key circuit includes a plurality of key resistors and a plurality of key switches, wherein the plurality of key resistors are respectively connected in series with the plurality of key switches; A self-excited oscillation circuit connected to the key circuit via a transformer; The key circuit is configured to connect a first key resistor to the self-excited oscillation circuit through the transformer, the self-excited oscillation circuit is configured to adjust the amplitude of a sinusoidal oscillation signal based on the resistance value of the first key resistor, and the frequency of the sinusoidal oscillation signal is different from the frequency of an external high-frequency energy signal; a detection circuit connected to the output terminal of the self-excited oscillation circuit and configured to determine a DC voltage signal based on the sinusoidal oscillation signal; The detection circuit is connected to the output end of the detection circuit and is configured to determine the conduction states of the plurality of key switches based on the DC voltage signal.
2. The key detection circuit according to claim 1, wherein: The self-excited oscillation circuit comprises: a second resistor and a seventh resistor; a transistor, wherein the base of the transistor is connected to an external power supply via the second resistor, the emitter of the transistor is grounded via the seventh resistor, and the collector of the transistor is connected to the primary winding of the transformer; a third capacitor, one end of the third capacitor being connected to the primary winding of the transformer, and the other end of the third capacitor being connected to the seventh resistor; A fourth capacitor, one end of the fourth capacitor is connected to the external power supply, and the other end is connected to the seventh resistor.
3. The key detection circuit according to claim 2, wherein: The self-excited oscillation circuit is configured to adjust the frequency of the sinusoidal oscillation signal based on parameters of the primary winding of the transformer, parameters of the third capacitor, and parameters of the fourth capacitor.
4. The key detection circuit according to claim 2, wherein: The detection circuit comprises: a first diode and a seventh capacitor; One end of the seventh capacitor is connected to the primary winding of the transformer through the first diode, and the other end is grounded.
5. The key detection circuit according to claim 4, characterized in that: The detection circuit further includes: Eighth resistor and potentiometer; One end of the eighth resistor is connected to the seventh capacitor, and the other end is grounded through the potentiometer.
6. The key detection circuit according to claim 5, characterized in that: The detection circuit further includes: a second diode and a ninth resistor; One end of the ninth resistor is connected to the primary winding of the transformer, and the other end is connected to the anode of the second diode.
7. The key detection circuit according to claim 6, characterized in that: The detection circuit further includes: A sixth capacitor is connected to the potentiometer.
8. The key detection circuit according to claim 4, characterized in that: The self-excited oscillation circuit further includes: a first capacitor, a second capacitor, and a fifth capacitor; One end of the second capacitor is connected to the base of the transistor, and the other end is connected to the first capacitor; One end of the fifth capacitor is connected to the primary winding of the transformer, and the other end is connected to the anode of the first diode.
9. The key detection circuit according to claim 1, wherein: The key circuit also includes: A first resistor and a sixth resistor, wherein the first resistor and the sixth resistor are both connected to the secondary winding of the transformer.
10. An electronic device, characterized in that: The invention comprises the key detection circuit according to any one of claims 1 to 9.