Virtual connection detection circuit, device and method

Abstract

The invention discloses a virtual connection detection circuit, device and method, and relates to the technical field of circuits, the circuit comprises a comparator, a first resistor, a voltage divider and an indicator; the positive input end of the comparator is used for being connected with a moving point of the voltage divider, the first end of the voltage divider is used for being connected with power supply voltage, and the second end of the voltage divider is used for being grounded; the negative input end of the comparator is used for being connected with the first end of the first resistor, the second end of the first resistor is grounded, the negative input end of the comparator is further used for being connected with the first end of a wire to be detected, and the second end of the wire to be detected is used for being connected with input voltage; the output end of the comparator is used for being connected with an indicator, and the indicator is used for indicating a detection result. The circuit can detect the virtual connection phenomenon, thereby guaranteeing the normal connection of a lead, and reducing the error of a test result.

Description

Technical Field

[0001] This application relates to the field of circuit technologies, and particularly to an open circuit detection circuit, device, and method. Background Art

[0002] In the field of automotive engineering, bench testing is a key technical link connecting design solutions to product implementation. As the core means of verifying vehicle performance indicators, it not only undertakes the task of evaluating the reliability of key modules such as the power system and the electronic control system, but also provides a quantitative basis for optimizing design parameters through measured data, controlling product quality from the source to meet strict industry regulations and safety standards. Before starting this precise test work, engineers must complete a basic but cumbersome pre-task, that is, the reliable connection of the on-vehicle wire system, including but not limited to CAN bus communication wires and low-voltage power supply wires.

[0003] Early wire connections relied on pure manual operations: engineers needed to use wire stripping tools to remove the insulation layer of the wire, twist the copper cores, and wrap them with insulating tape. This solution ensured the basic connectivity of the test circuit for a long time with the stability of mechanical physical connections. With the increasing demand for test efficiency, standardized wire connection terminals emerged. These prefabricated components shortened the connection time of a single wire from the minute level to the second level through the quick docking of plugs and sockets, significantly improving the bench setup efficiency.

[0004] However, the method of connecting wires based on standardized wire connection terminals, although it can achieve the purpose of quick connection, is prone to open circuit phenomena. Due to the existence of open circuit phenomena, test signals will be distorted during transmission, resulting in large errors in test results. Summary of the Invention

[0005] This application provides an open circuit detection circuit, device, and method that can detect open circuit phenomena, thereby ensuring normal wire connection and reducing errors in test results.

[0006] To achieve the above object, this application adopts the following technical solutions: In a first aspect, this application provides an open circuit detection circuit, and the circuit includes: a comparator, a first resistor, a voltage divider, and an indicator; The positive input terminal of the comparator is used to connect to the moving point of the voltage divider. The first end of the voltage divider is used to connect to the power supply voltage, and the second end of the voltage divider is used to connect to the ground. The power supply voltage is used to supply power to the voltage divider and the comparator; The negative input terminal of the comparator is used to connect to the first end of the first resistor. The second end of the first resistor is grounded. The negative input terminal of the comparator is also used to connect to the first end of the wire to be detected, and the second end of the wire to be detected is used to connect to the input voltage; The output terminal of the comparator is used to connect to an indicator, and the indicator is used to indicate the detection result.

[0007] Optionally, the circuit further includes: a peak detection circuit and a filtering circuit; The output terminal of the peak detection circuit is connected to the first end of the first resistor, the input terminal of the peak detection circuit is connected to the output terminal of the filtering circuit, and the input terminal of the filtering circuit is connected to the first end of the wire to be detected; The filtering circuit is used to filter out interference signals and output signals in a target frequency band; The peak detection circuit is used to convert the signals in the target frequency band into DC signals.

[0008] Optionally, the peak detection circuit includes a first diode and a first capacitor; The first end of the first capacitor is connected to the cathode of the first diode, the first end of the first capacitor is connected to the negative input terminal of the comparator, and the second end of the first capacitor is grounded; the anode of the first diode is used to connect to the filtering circuit.

[0009] Optionally, the filtering circuit includes a high-pass filtering circuit and a low-pass filtering circuit; The high-pass filtering circuit includes a second capacitor and a second resistor, and the low-pass filtering circuit includes a third capacitor and a third resistor; The first end of the second capacitor is connected to the first end of the wire to be detected, the second end of the second capacitor is connected to the first end of the second resistor, and the second end of the second resistor is grounded; The first end of the third resistor is connected to the second end of the second capacitor, the second end of the third resistor is connected to the first end of the third capacitor, and the second end of the third capacitor is grounded; The second end of the third resistor is connected to the anode of the first diode.

[0010] Optionally, the circuit further includes a fourth capacitor; The first end of the fourth capacitor is connected to the second end of the wire to be detected, and the second end of the fourth capacitor is used to connect to the power supply voltage.

[0011] Optionally, the voltage divider is further used to adjust the voltage provided by the power supply voltage to the positive input terminal of the comparator.

[0012] Optionally, the power supply terminal of the comparator is used to connect to the power supply voltage, and the ground terminal of the comparator is used to be grounded.

[0013] Optionally, when the voltage at the positive input terminal of the comparator is greater than the voltage at the negative input terminal of the comparator, the output terminal of the comparator outputs the power supply voltage.

[0014] Optionally, the indicator includes a light-emitting device, a sound-emitting device, or a vibration device.

[0015] In a second aspect, the present application provides a virtual connection detection device, which includes a wire fixing device and an optional virtual connection detection circuit in any one of the first aspects.

[0016] In a third aspect, the present application provides a method for a virtual connection detection circuit applied to an optional virtual connection detection circuit in any one of the first aspects. The method includes: Obtain the indication content of the indicator; Determine the detection result of the virtual connection detection according to the indication content.

[0017] It can be seen from the above technical solutions that the present application has at least the following beneficial effects: The present application provides a virtual connection detection circuit, which includes a comparator, a first resistor, a voltage divider, and an indicator. The positive input terminal of the comparator is used to connect to the moving point of the voltage divider. The first end of the voltage divider is used to connect to the power supply voltage, the second end of the voltage divider is used to be grounded, the negative input terminal of the comparator is used to connect to the first end of the first resistor, the second end of the first resistor is grounded, the negative input terminal of the comparator is also used to connect to the first end of the wire to be detected, the second end of the wire to be detected is used to connect to the input voltage, the output terminal of the comparator is used to connect to the indicator, and the indicator is used to indicate the detection result. In the circuit of the present application, the voltage at the positive input terminal of the comparator can be set through the voltage divider. After the setting is completed, if there is a virtual connection in the wire to be detected, a part of the voltage will be diverted from both ends of the first resistor, thereby reducing the voltage across the first resistor, that is, the voltage at the negative input terminal will decrease. When the voltage at the positive input terminal is reasonably set, the voltage at the negative input terminal will be lower than the voltage at the positive input terminal. At this time, the output terminal of the comparator will output the power supply voltage to the indicator, and the indicator will indicate the detection result of the virtual connection.

[0018] It should be understood that the descriptions of technical features, technical solutions, beneficial effects or similar languages in this application do not imply that all features and advantages can be achieved in any single embodiment. On the contrary, it can be understood that the description of features or beneficial effects means that specific technical features, technical solutions or beneficial effects are included in at least one embodiment. Therefore, the descriptions of technical features, technical solutions or beneficial effects in this specification do not necessarily refer to the same embodiment. Furthermore, the technical features, technical solutions and beneficial effects described in this embodiment can be combined in any appropriate manner. Those skilled in the art will understand that an embodiment can be implemented without one or more specific technical features, technical solutions or beneficial effects of a specific embodiment. In other embodiments, additional technical features and beneficial effects can also be identified in specific embodiments that do not embody all embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. is a schematic diagram of an open-circuit detection circuit provided by an embodiment of the present application; Figure 2 FIG. is a schematic diagram of another open-circuit detection circuit provided by an embodiment of the present application; Figure 3 FIG. is a schematic diagram of a peak detection circuit provided by an embodiment of the present application; Figure 4 FIG. is a schematic diagram of a filter circuit provided by an embodiment of the present application; Figure 5 FIG. is a design scheme diagram of an open-circuit detection circuit provided by an embodiment of the present application; Figure 6 FIG. is a schematic diagram of an open-circuit detection device provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The terms "first", "second", "third", etc. in the specification and drawings of this application are used to distinguish different objects, rather than to limit a specific order.

[0021] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or having more advantages than other embodiments or design schemes. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0022] For the sake of clear and concise description of the following embodiments, a brief introduction to the related technologies is given first: The virtual connection of a wire refers to an abnormal connection state in an electrical connection where, although the wire appears to be in good contact with a terminal, device pin, or other conductor, there is actually insufficient contact and unstable conductivity. This hidden fault is manifested as not being completely separated physically, but having a defect in the electrical connection. The difference between a virtual connection and an open circuit is that in the case of a virtual connection, the conductive path is not completely broken, but there is a contact defect, manifested as an abnormally increased contact resistance and an unstable connection state. When a simulated signal (such as a sensor voltage signal) has a virtual connection, an additional voltage drop or noise is introduced due to the contact resistance, resulting in distorted and fluctuating test data (such as error codes and frame loss in a CAN bus signal); a virtual connection of a digital signal may cause edge jitter and logic level jumps, leading to misjudgment by the control module (such as an intermittent restart of a device due to a virtual connection of a low-voltage power line). It can be seen that a virtual connection of a wire will result in a large signal error.

[0023] In view of this, an embodiment of the present application provides a virtual connection detection circuit. As Figure 1 shown, this figure is a schematic diagram of a virtual connection detection circuit provided by an embodiment of the present application.

[0024] This virtual connection detection circuit includes a comparator U3, a first resistor R5, a voltage divider RP, and an indicator Vi.

[0025] The positive input terminal of the comparator U3 is used to connect to the moving point D of the voltage divider RP. The first end of the voltage divider RP is used to connect to the power supply voltage VCC, and the second end of the voltage divider RP is used to ground. The power supply voltage VCC is used to supply power to the voltage divider RP and the comparator U3.

[0026] The negative input terminal of the comparator U3 is used to connect to the first end of the first resistor R5. The second end of the first resistor R5 is grounded. The negative input terminal of the comparator U3 is also used to connect to the first end of the wire RC to be detected. The second end of the wire RC to be detected is used to connect to the input voltage V_in. Here, the wire RC to be detected refers to a part of the wire in the circuit to be detected, such as a wire containing a joint.

[0027] The output terminal of the comparator U3 is used to connect to the indicator Vi, and this indicator Vi is used to indicate the detection result.

[0028] From Figure 1It can be seen that the positive input voltage V3 at the positive input terminal of the comparator U3 will no longer change after the moving point D of the voltage divider is fixed (when the power supply voltage remains unchanged). From the virtual connection phenomenon, it can be known that after a virtual connection occurs, the resistance at the virtual connection will increase abnormally. The input voltage V_in is divided by the first resistor R5 and the wire to be detected RC. When the resistance at the virtual connection increases abnormally, the voltage across the first resistor R5 will decrease. Thus, the negative input voltage V4 at the negative input terminal of the comparator U3 will decrease. By reasonably setting the position of the moving point D of the voltage divider RP, it can be ensured that when there is a virtual connection, the negative input voltage V4 of the comparator U3 is less than the positive input voltage V3. Furthermore, the output terminal of the comparator U3 outputs the power supply voltage, and the indicator Vi can indicate the detection result.

[0029] In the case of no virtual connection, the resistance of the wire to be detected RC is almost zero, and the input voltage V_in is almost entirely applied to the first resistor R5. Consequently, the negative input voltage V4 at the negative input terminal of the comparator U3 approaches the input voltage V_in. By reasonably setting the position of the moving point D of the voltage divider RP, it can be ensured that when there is no virtual connection, the negative input voltage V4 of the comparator U3 is greater than the positive input voltage V3. Furthermore, the output terminal of the comparator U3 does not output voltage, and the indicator Vi can indicate the detection result.

[0030] As described above in conjunction with Figure 1 , the principle of the virtual connection detection circuit provided in the embodiments of the present application has been introduced. Next, the overall technical solution of the present application will be introduced.

[0031] As Figure 2 shown, this figure is a schematic diagram of another virtual connection detection circuit provided in the embodiments of the present application. This virtual connection detection circuit is refined on the basis of Figure 1 , and will be introduced in detail below.

[0032] In some examples, this virtual connection detection circuit further includes a peak detection circuit 300 and a filtering circuit 400; the peak detection circuit is as Figure 3 shown, and the filtering circuit is as Figure 4 shown. Continuing to refer to Figure 2 , the output terminal of the peak detection circuit 300 is connected to the first end of the first resistor R5, the input terminal of the peak detection circuit 300 is connected to the output terminal of the filtering circuit 400, and the input terminal of the filtering circuit 400 is connected to the first end of the wire to be detected RC. Among them, the filtering circuit 400 is used to filter out interference signals and output signals in the target frequency band, and the peak detection circuit 300 is used to convert the signals in the target frequency band into DC signals.

[0033] The filtering circuit 400 includes a high-pass filtering circuit 401 and a low-pass filtering circuit 402. The high-pass filtering circuit 401 includes a second capacitor C2 and a second resistor R3, and the low-pass filtering circuit 402 includes a third capacitor C5 and a third resistor R4; the first end of the second capacitor C2 is connected to the first end of the wire RC to be detected, the second end of the second capacitor C2 is connected to the first end of the second resistor R3, and the second end of the second resistor R3 is grounded; the first end of the third resistor R4 is connected to the second end of the second capacitor C2, the second end of the third resistor R4 is connected to the first end of the third capacitor C5, and the second end of the third capacitor C5 is grounded; the second end of the third resistor R4 is connected to the anode of the first diode D1.

[0034] For the low-pass filtering circuit, the calculation method of the cut-off frequency is as follows:

[0035] In the formula, represents the cut-off frequency of the low-pass filtering circuit, represents the resistance value of the third resistor, represents the capacitance value of the third capacitor.

[0036] For the high-pass filtering circuit, the calculation method of the cut-off frequency is as follows:

[0037] In the formula, represents the cut-off frequency of the high-pass filtering circuit, represents the resistance value of the second resistor, represents the capacitance value of the second capacitor.

[0038] In this way, the high-pass filtering circuit 401 and the low-pass filtering circuit 402 can form a band-pass filter, and the band-pass frequency range is: , where is the band-pass frequency range of the band-pass filter.

[0039] The peak detection circuit 300 is used to convert the target frequency band signal passing through the band-pass filter composed of the high-pass filtering circuit 401 and the low-pass filtering circuit 402 into a DC signal, where the target frequency band signal refers to the signal within the band-pass frequency range of the band-pass filter. After converting the target frequency band signal into a DC signal, it is convenient to input it to the comparator U3 for virtual connection judgment later.

[0040] In some examples, the peak detection circuit includes a first diode D1 and a first capacitor C6. The first end of the first capacitor C6 is connected to the cathode of the first diode D1, the first end of the first capacitor C6 is connected to the negative input terminal of the comparator U3, and the second end of the first capacitor C6 is grounded; the anode of the first diode D1 is used to connect to the filtering circuit 400.

[0041] The working principle of the peak detection circuit 300 is as follows: during the positive half-cycle of the target frequency band signal, the first diode D1 is turned on at this time, and the current charges the first capacitor C6 through the first diode. The voltage across the first capacitor C6 rises to the peak value of the target frequency band signal, that is, . Among them, represents the voltage across the first capacitor C6, represents the peak value of the target frequency band signal, represents the forward voltage drop of the first diode. For example, = 0.3V. During the negative half-cycle stage of the target frequency band signal, the first diode D1 is in the cut-off stage at this time. Since the impedance of the first diode D1 is very large when passing through it in the reverse direction, the discharge speed of the first capacitor C6 is extremely slow and can basically maintain the peak voltage. Since the first capacitor C6 charges quickly but discharges extremely slowly, the target frequency band signal is successfully converted into a DC signal, and the voltage of the first capacitor C6 is approximately equal to the peak voltage of the target frequency band signal.

[0042] In some examples, the virtual connection detection circuit further includes a fourth capacitor C1. The first end of the fourth capacitor C1 is connected to the second end of the wire RC to be detected, and the second end of the fourth capacitor C1 is used to connect to the power supply voltage. This fourth capacitor is a coupling capacitor, which is used to allow AC signals to pass through and isolate DC signals, that is, to allow high-frequency square wave signals to flow to the wire RC to be detected and prevent the direct current in the line to be detected where the wire RC to be detected is located from flowing back to the virtual connection detection circuit, thereby causing great interference to the detection result of the virtual connection detection circuit.

[0043] In some embodiments, the voltage divider RP is further used to adjust the voltage provided by the power supply voltage to the positive input terminal of the comparator U3. For example, when the moving point D of the voltage divider RP moves towards the first end of the voltage divider RP, the resistance value between the moving point D of the voltage divider RP and the first end of the voltage divider RP becomes smaller, that is, the voltage division becomes smaller, and then the voltage provided by the power supply voltage to the positive input terminal of the comparator U3 will become larger, that is, the voltage threshold for comparison is increased; when the moving point D of the voltage divider RP moves towards the second end of the voltage divider RP, the resistance value between the moving point D of the voltage divider RP and the first end of the voltage divider RP becomes larger, that is, the voltage division becomes larger, and then the voltage provided by the power supply voltage to the positive input terminal of the comparator U3 will become smaller, that is, the voltage threshold for comparison is decreased. In this way, the virtual connection detection circuit provided by the embodiments of the present application can adjust the voltage threshold for comparison based on the actual detection scenario, so that the virtual connection detection circuit can be compatible with a variety of detection scenarios and expand the detection range.

[0044] In some examples, the power supply terminal of the comparator U3 is used to connect to the power supply voltage, and the ground terminal of the comparator U3 is used to ground. Exemplarily, the open-circuit detection circuit includes a voltage regulator U1, which is used to ensure the stability of the power supply voltage. For example, the voltage regulator U1 can be a Low Dropout Regulator (LDO) with an output voltage of 3.3V. The voltage regulator U1 includes three pins: the U1_1-in pin (used to connect to the power supply voltage), the U1_2-GND pin (used to ground), and the U1_3-OUT pin (used to connect to the power supply terminal of the comparator U3 and also connected to the first end of the voltage divider RP).

[0045] In some examples, the open-circuit detection circuit includes a high-frequency oscillation circuit, which includes a timer U2, a fourth resistor R1, a fifth resistor R2, a fifth capacitor C3, and a sixth capacitor C4. Among them, the timer U2 can specifically be a 555 timer, and the pins and functions of the timer U2 are shown in Table 1 below.

[0046] Table 1: Pins and Functions of U2 Pin Function U2_1 - GND Connected to the common ground of the circuit U2_2 - TRIG Trigger input terminal. The voltage of this pin can be used to determine whether it is less than one - third of VCC (power supply voltage). U2_3 - OUT Output terminal, outputs a high - frequency square - wave signal. The absolute value of the high level is approximately equal to the value of VCC. U2_4 - RESET Clear terminal. It should be connected to a high level during normal operation. U2_5 - CONT Control voltage terminal. Generally not used. It should be grounded through a 10nF capacitor to prevent high - frequency interference. U2_6 - THRES This pin will determine whether its voltage is greater than two - thirds of VCC. U2_7 - DISCH Discharge terminal U2_8 - VCC Connected to the positive pole of the power supply Among them, for the 555 timer, the U2_1-GND pin is grounded, the U2_8-VCC pin and the U2_4-RESET pin are connected to the power supply, the U2_5-CONT pin is connected to a 10nF capacitor and then grounded, and the U2_3-OUT pin is the output terminal. The connection methods of the U2_2-TRIG pin, the U2_6-THRES pin, and the U2_7-DISCH pin are different according to different application scenarios. In this application, an astable oscillation circuit composed of a 555 timer, capacitors, and resistors in combination is used to generate a high-frequency square wave signal, and the circuit has a low cost and a small volume.

[0047] Combined with Figure 2As shown, the first end of the fourth resistor R1 is connected to the U1_3 - OUT pin of the voltage regulator U1, the second end of the fourth resistor R1 is connected to the first end of the fifth resistor R2, the second end of the fifth resistor R2 is connected to the U2_2 - TRIG pin of the timer U2, and the first end of the fifth resistor R2 is connected to the U2_7 - DISCH pin of the timer U2; the U2_1 - GND pin of the timer U2 is grounded, the U2_2 - TRIG pin is connected to the first end of the fifth capacitor C3, the second end of the fifth capacitor C3 is grounded, the U2_3 - OUT pin is connected to the second end of the fourth capacitor C1, the U2_4 - RESET pin is connected to the U1_3 - OUT pin of the voltage regulator U1, the U2_5 - CONT pin is connected to the first end of the sixth capacitor C4, the second end of the sixth capacitor C4 is grounded, the U2_6 - THRES pin is connected to the first end of the fifth capacitor C3, and the U2_8 - VCC pin is connected to the U1_3 - OUT pin of the voltage regulator U1. The frequency calculation formula for the high - frequency square - wave signal that the high - frequency oscillation circuit can generate is:

[0048] Wherein, represents the high - frequency square - wave signal that the high - frequency vibration circuit can generate, represents the resistance value of the fourth resistor, represents the resistance value of the fifth resistor, represents the capacitance value of the fifth capacitor.

[0049] In some examples, the indicator Vi includes a light - emitting device, a sound - emitting device, or a vibration device. When the indicator Vi is a light - emitting device, the light - emitting device includes a light - emitting element and a protection resistor R6. Among them, the light - emitting element can be a light - emitting diode LED1. The protection resistor R6 is used to limit the current flowing through the light - emitting diode LED1. Wherein, the first end of the protection resistor R6 is connected to the output end of the comparator U3, the second end of the protection resistor R6 is connected to the anode of the light - emitting diode LED1, and the cathode of the light - emitting diode LED1 is grounded. When the voltage at the negative input terminal of the comparator U3 is less than the voltage at the positive input terminal, the output terminal of the comparator U3 outputs the power supply voltage. Thus, there is current flowing through the light - emitting device, and further the light - emitting element emits light. Based on this light emission, the user can know that there is a loose connection in the wire RC to be detected. Otherwise, there is no loose connection.

[0050] When the indicator Vi is a sound - emitting device, the sound - emitting device includes a sound - emitting element and a protection resistor. Among them, the sound - emitting element can be a buzzer, and the protection resistor is used to limit the current flowing through the buzzer. The first end of the protection resistor is connected to the output terminal of the comparator U3, the second end of the protection resistor is connected to one end of the buzzer, and the other end of the buzzer is grounded. When the voltage at the negative input terminal of the comparator U3 is less than the voltage at the positive input terminal, the output terminal of the comparator U3 outputs the power supply voltage. Thus, current flows through the sound - emitting device, and then the sound - emitting element emits a sound. Based on this sound, the user can know that there is a loose connection in the wire RC to be detected. Otherwise, there is no loose connection situation.

[0051] When the indicator Vi is a vibration device, the vibration device includes a vibration element and a protection resistor. Among them, the vibration element can be a vibration motor, and the protection resistor is used to limit the current flowing through the vibration motor. The first end of the protection resistor is connected to the output terminal of the comparator U3, the second end of the protection resistor is connected to one end of the vibration motor, and the other end of the vibration motor is grounded. When the voltage at the negative input terminal of the comparator U3 is less than the voltage at the positive input terminal, the output terminal of the comparator U3 outputs the power supply voltage. Thus, current flows through the vibration device, and then the vibration element starts to vibrate. Based on this vibration, the user can know that there is a loose connection in the wire RC to be detected. Otherwise, there is no loose connection situation.

[0052] Based on the above description, the present invention aims at the common loose - connection problem in the use of small - wire connection terminals to achieve rapid wire connection in bench testing, and proposes a loose - connection detection solution integrated inside the terminal, that is, a loose - connection detection circuit. This loose - connection detection circuit is based on the principles of high - frequency AC injection, band - pass filtering, peak detection, and voltage division, and can monitor the loose - connection situation at the crimping point of the wire inside the wiring terminal in real time. Once a loose - connection phenomenon is detected, the indicator of the loose - connection detection circuit immediately gives a corresponding prompt to ensure timely discovery and handling of potential loose - connection faults. The technical solution of this application not only improves the reliability of wire connection, but also significantly enhances the safety and efficiency of the bench - testing process, effectively avoiding signal distortion, transmission interruption, and possible safety hazards caused by loose connections.

[0053] As Figure 5 shown, this figure is a design diagram of a loose - connection detection circuit provided by an embodiment of this application. The loose - connection detection circuit includes a power - supply module 601, a high - frequency oscillation module 602, a band - pass filter 603, a peak - detection module 604, and a loose - connection alarm module 605.

[0054] Among them, the power supply module 601 is composed of a battery S1 and a voltage regulator U1, and is used to provide a stable voltage for the open circuit detection circuit; the high-frequency oscillation module 602 is composed of a timer U2, a fourth resistor R1, a fifth resistor R2, a fifth capacitor C3 and a sixth capacitor C4, and is used to emit a high-frequency square wave signal, that is, to convert the DC signal input by the power supply module 601 into an AC signal. The high-frequency square wave signal passes through the fourth capacitor C1 (the function of the fourth capacitor C1 is to allow the AC signal to pass through and isolate the DC signal, that is, to allow the high-frequency square wave signal to flow to the wire to be detected RC, and prevent the direct current in the circuit to be detected where the wire to be detected RC is located from flowing back to the open circuit detection circuit, thereby causing great interference to the detection result of the open circuit detection circuit) and is transmitted to the wire to be detected RC, passes through the wire to be detected RC, and enters the band-pass filter 603; the band-pass filter is composed of a high-pass filter circuit and a low-pass filter circuit, and is used to screen out the target frequency band signal (based on the band-pass filter to filter out interference signals such as low-frequency direct current and high-frequency noise, and leave the target frequency band signal). The target frequency band signal can adjust the frequency band range by configuring the component parameters, and this signal range should include the frequency value of the aforementioned high-frequency square wave signal; the peak detection module 604 is composed of a first diode and a first capacitor C6, and is used to convert the target frequency band signal into a DC signal (the value of this DC signal is approximately equal to the positive half-cycle peak value of the AC square wave signal in the target frequency band); the open circuit alarm module 605 is composed of a comparator U3, a voltage divider RP, a first resistor R5 and an indicator. The indicator is used to indicate whether there is an open circuit. Exemplarily, when the indicator is a light-emitting device, the light-emitting device includes a light-emitting element and a protection resistor. When the light-emitting element emits light, it is determined that there is an open circuit fault, and if it does not emit light, the detection continues. If the wire to be detected RC is in an open circuit state, then the open circuit resistance generated by it will cause a voltage drop phenomenon in the circuit. At this time, the monitored voltage value will be lower than the voltage threshold set by the open circuit alarm module 605, resulting in the light-emitting diode LED1 emitting light. If the monitored voltage value is higher than the voltage threshold, it is considered that the wire to be detected RC is in a normal state.

[0055] To make the technical solution of the present application clearer, the following will be introduced by way of example with reference to Figure 2 the schematic diagram of the open circuit detection circuit shown.

[0056] Exemplarily, the voltage output by the power supply module 601 composed of the battery S1 and the voltage regulator U1 is 3.3V, the resistance value of the fourth resistor R1 is 4700Ω, the resistance value of the fifth resistor R2 is 4700Ω, the resistance value of the second resistor R3 is 10000Ω, the resistance value of the third resistor R4 is 10Ω, the resistance value of the first resistor R5 is 100Ω, the resistance value of the protection resistor R6 is 1000Ω, the capacitance value of the fourth capacitor C1 is 100nF, the capacitance value of the second capacitor C2 is 100nF, the capacitance value of the fifth capacitor C3 is 10nF, the capacitance value of the sixth capacitor C4 is 10nF, the capacitance value of the third capacitor C5 is 1uF, the capacitance value of the first capacitor C6 is 1uF, the voltage divider RP is 10000Ω. The positive input voltage V3 of the non-inverting input terminal of the comparator U3 is adjusted to 0.6V by using the voltage divider RP, and the voltage drop VD1 flowing through the first diode D1 is 0.3V. Assuming that the voltage does not decay after passing through the timer U2 and there is no loose connection, the resistance value of the wire RC to be detected is 0Ω, and when there is a loose connection, the resistance value of the wire RC to be detected is 1000Ω. Among them, the voltage divider RP can be a potentiometer. The indicator is a light-emitting device.

[0057] From the known conditions, the frequency of the high-frequency square wave signal emitted by the high-frequency oscillation module can be calculated as:

[0058] represents the high-frequency square wave signal emitted by the high-frequency oscillation module, represents the resistance value of the fourth resistor, represents the resistance value of the fifth resistor, represents the capacitance value of the fifth capacitor.

[0059] Since the high level of the high-frequency square wave signal emitted by the U2_3 - OUT pin of the timer U2 in the high-frequency oscillation module is approximately the voltage connected to the U2_8 - VCC pin of the timer U2, then there is , represents the output voltage of the timer U2.

[0060] From the known conditions, the cut-off frequencies of the high-pass filter circuit and the low-pass filter circuit can be calculated respectively as:

[0061]

[0062] Thus, it can be known that the passband frequency range of the band-pass filter is:

[0063] Thus, it can be known that the high-frequency square wave signal (frequency ) It can pass through a band-pass filter.

[0064] When there is a loose connection fault in the wire to be detected, the equivalent voltage-dividing resistor forming a voltage-dividing relationship with R5 in the loose connection detection circuit is:

[0065] Among them, is the equivalent voltage-dividing resistor, represents the resistance value of the wire to be detected, represents the impedance of the fourth capacitor C1, is the equivalent impedance of the low-pass filter circuit, is the equivalent impedance of the high-pass filter circuit.

[0066] It can be calculated by the following method:

[0067] Among them, represents the capacitance value of the fourth capacitor.

[0068] It can be calculated by the following method:

[0069] represents the resistance value of the third resistor, j represents the imaginary unit, represents the capacitance value of the third capacitor.

[0070] For taking the modulus, we can get:

[0071] Since the frequency of the high-frequency square wave signal emitted by the high-pass filter is much greater than its cut-off frequency , that is, , the equivalent impedance brought by the high-pass filter can be ignored, so .

[0072] Therefore, when there is no loose connection, the first equivalent voltage-dividing resistor forming a voltage-dividing relationship with the first resistor R5 in the loose connection detection circuit is: . Based on the voltage-dividing principle, when there is no loose connection, the voltage at the negative input terminal of the comparator U3 is: Among them, represents the voltage at the negative input terminal of the comparator U3 when there is no loose connection, represents the voltage across the first resistor R5, Represents the output voltage of the U2_3 - OUT pin of timer U2, represents the voltage across the first diode, represents the resistance value of the first resistor, represents the first equivalent voltage - dividing resistor when there is no loose connection.

[0073] Therefore, when the wire to be detected is not loose - connected:

[0074] Among them: is the voltage threshold adjusted by the voltage divider RP to the non - inverting input terminal of the comparator U3. For the comparator U3, at this time, the voltage of the inverting input terminal is greater than the voltage of the non - inverting input terminal, and its output terminal voltage is equal to the ground voltage, that is, 0V. At this time, the light - emitting diode LED1 does not emit light.

[0075] The second equivalent voltage - dividing resistor that forms a voltage - dividing relationship with the first resistor R5 in the loose - connection detection circuit when there is a loose connection is: = = = . Based on the voltage - dividing principle, the voltage of the inverting input terminal of the comparator U3 when there is a loose connection can be obtained is:

[0076] Therefore, when the wire to be detected is loose - connected:

[0077] For the comparator U3, at this time, the voltage of the non - inverting input terminal is greater than the voltage of the inverting input terminal, and its output terminal voltage is equal to the VCC voltage, that is, 3.3V. At this time, the light - emitting diode LED1 is powered on and emits light, realizing loose - connection alarm.

[0078] The technical solution of this application has the following beneficial effects: This invention patent solves the pain points of wiring in bench testing, that is, the problems of low wiring efficiency and low wiring reliability. It considers using a loose - connection detection integrated circuit to make up for the defect that it is impossible to judge whether there is a loose connection when using a quick - wiring terminal. It combines the wiring efficiency advantage of the quick - wiring terminal and the wiring reliability advantage of the loose - connection detection technology, effectively avoiding signal distortion, transmission interruption and other possible safety hazards caused by loose connection in the main circuit; This invention patent considers the problem that the DC signal of the original main circuit may interfere with the loose connection detection circuit during the bench test. It cleverly uses the principles of high-frequency injection and band-pass filtering to block the DC signal, screen the target frequency band signal sent by the loose connection detection circuit, and then uses the peak detection principle to process the passed target frequency band signal into a DC signal to provide DC support for the loose connection alarm module, improving the robustness of the loose connection detection integrated circuit; This invention patent also considers circuit adaptability. By configuring a potentiometer, the user can adjust the minimum alarm threshold of the loose connection detection voltage according to the actual situation of the circuit, making the adaptability of this loose connection detection circuit more flexible; While ensuring the functional integrity and performance, the present invention reduces the manufacturing cost and the occupation of physical space, which is particularly crucial for integrating the device into a small quick-connect terminal, meeting the requirements of a compact design without adding an additional cost burden.

[0079] The embodiment of the present application also provides a loose connection detection device, as Figure 6 shown. This figure is a schematic diagram of a loose connection detection device provided by the embodiment of the present application. The loose connection detection device includes a wire fixing device 701 and a loose connection detection circuit 702. Among them, the wire fixing device 701 and the loose connection detection circuit 702 can be arranged in a housing, and the housing can be made of flame-retardant nylon material. The wire fixing device 701 is used to fix the wire to be detected, and the loose connection detection circuit 702 can be the loose connection detection circuit introduced in the foregoing embodiments.

[0080] The present application does not specifically limit the specific structure of the wire fixing device.

[0081] The embodiment of the present application also provides a loose connection detection method, which is applied to any optional loose connection detection circuit in the foregoing embodiments. This method can be executed by a processing device, and this method includes: S701: The processing device obtains the indication content of the indicator.

[0082] The processing device can obtain the indication content of the indicator through a sensor, or determine the indication content by receiving the signal sent by the indicator. Among them, the indication content can be the flashing of a lamp (for example, the corresponding indicator is a light-emitting diode).

[0083] S702: The processing device determines the detection result of the loose connection detection according to the indication content.

[0084] After the processing device determines the indication content, it can judge the detection result corresponding to the indication content based on the pre-set mapping relationship between the content and the result. For example, when the indication content is the flashing of a lamp, the corresponding inspection result is that there is a loose connection problem.

[0085] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims

1. A virtual connection detection circuit, characterized in that, The circuit includes: a comparator, a first resistor, a voltage divider, and an indicator; The positive input terminal of the comparator is used to connect to the moving point of the voltage divider. The first end of the voltage divider is used to connect to the power supply voltage, and the second end of the voltage divider is used to connect to ground. The power supply voltage is used to supply power to the voltage divider and the comparator; The negative input terminal of the comparator is used to connect to the first end of the first resistor. The second end of the first resistor is grounded. The negative input terminal of the comparator is also used to connect to the first end of the wire to be detected, and the second end of the wire to be detected is used to connect to the input voltage; The output terminal of the comparator is used to connect to the indicator, and the indicator is used to indicate the detection result.

2. The virtual connection detection circuit according to claim 1, characterized in that The circuit further includes: a peak detection circuit and a filtering circuit; The output terminal of the peak detection circuit is connected to the first end of the first resistor. The input terminal of the peak detection circuit is connected to the output terminal of the filtering circuit, and the input terminal of the filtering circuit is connected to the first end of the wire to be detected; The filtering circuit is used to filter out interference signals and output signals in the target frequency band; The peak detection circuit is used to convert the signals in the target frequency band into DC signals.

3. The virtual connection detection circuit according to claim 2, wherein The peak detection circuit includes a first diode and a first capacitor; The first end of the first capacitor is connected to the cathode of the first diode. The first end of the first capacitor is connected to the negative input terminal of the comparator, and the second end of the first capacitor is grounded; the anode of the first diode is used to connect to the filtering circuit.

4. The virtual connection detection circuit according to claim 3, wherein The filtering circuit includes a high-pass filtering circuit and a low-pass filtering circuit; The high-pass filtering circuit includes a second capacitor and a second resistor, and the low-pass filtering circuit includes a third capacitor and a third resistor; The first end of the second capacitor is connected to the first end of the wire to be detected. The second end of the second capacitor is connected to the first end of the second resistor, and the second end of the second resistor is grounded; The first end of the third resistor is connected to the second end of the second capacitor. The second end of the third resistor is connected to the first end of the third capacitor, and the second end of the third capacitor is grounded; The second end of the third resistor is connected to the anode of the first diode.

5. The virtual connection detection circuit according to claim 1, wherein The circuit further includes a fourth capacitor; The first end of the fourth capacitor is connected to the second end of the wire to be detected, and the second end of the fourth capacitor is used to connect to the power supply voltage.

6. The virtual connection detection circuit according to claim 1, characterized in that, When the moving point of the voltage divider moves towards the first end of the voltage divider, the resistance value between the moving point of the voltage divider and the first end of the voltage divider becomes smaller; when the moving point of the voltage divider moves towards the second end of the voltage divider, the resistance value between the moving point of the voltage divider and the first end of the voltage divider becomes larger.

7. The virtual connection detection circuit according to claim 6, wherein, When the voltage at the positive-phase input terminal of the comparator is greater than the voltage at the negative input terminal of the comparator, the output terminal of the comparator outputs the power supply voltage.

8. The virtual connection detection circuit according to any one of claims 1 to 7, characterized in that The indicator includes a light-emitting device, a sound-emitting device, or a vibration device.

9. A virtual connection detection device, characterized in that, It includes a wire fixing device and the loose connection detection circuit according to any one of claims 1 to 8.

10. A virtual connection detection method, characterized in that, Applied to the loose connection detection circuit according to any one of claims 1 to 8, the method includes: Obtaining the indication content of the indicator; Determining the detection result of the loose connection detection according to the indication content.

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