Limiting detection circuit

Abstract

The utility model relates to the technical field of medical instruments, in particular to a limit detection circuit, which comprises a distance sensing module used for outputting a first voltage signal when a detected object moves to a preset distance range; the sampling module is connected with the distance sensing module and is used for sampling the first voltage signal; and the comparison module is connected with the sampling module and is used for acquiring a reference threshold signal and the first voltage signal and outputting a working signal or a closing signal according to the reference threshold signal and the first voltage signal. The limiting detection circuit is used for detecting and limiting the moving distance of the detected object, non-contact type limiting control over the detected object can be achieved, and the problem that a mechanical limiting structure and the detected object are possibly damaged due to contact and collision is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of medical equipment, in particular to a limit detection circuit. Background Art

[0002] Chest compression is an important treatment link in CPR (Cardiopulmonary Resuscitation). In some cases, chest compression can be implemented with the help of a chest compression machine. The pressing head of the chest compression machine performs reciprocating telescopic motion, and the extension and retraction of the pressing head are controlled by a motor encoder and a displacement sensor. In the prior art, for safety reasons, in order to prevent the pressing head from pressing too much on the patient's chest, a mechanical limit structure is set inside the chest compression machine, and the mechanical limit structure is used to limit the retractable limit position of the pressing head. However, the collision between the mechanical limit structure and the structure inside the chest compression machine may cause damage to the chest compression machine and affect the service life of the chest compression machine. Therefore, it is necessary to improve the existing technology. Utility Model Content

[0003] Based on this, it is necessary to provide a limit detection circuit to address the problems existing in existing chest compression machines.

[0004] A limit detection circuit includes a distance sensing module, which is used to output a first voltage signal when the object to be detected moves within a preset distance range; a sampling module, which is connected to the distance sensing module and is used to sample the first voltage signal; and a comparison module, which is connected to the sampling module and is used to obtain a reference threshold signal and the first voltage signal, and output a working signal or a shutdown signal according to the reference threshold signal and the first voltage signal.

[0005] In one embodiment, the distance sensing module includes a first detection unit and a pulse input unit connected to the first detection unit. When the object to be measured moves to within a preset distance range, the first detection unit and the object to be measured form a coupling capacitor; and the pulse input unit outputs a first voltage signal according to the coupling capacitor.

[0006] In one embodiment, the distance sensing module further includes a second detection unit, which is disposed on the object to be measured. The second detection unit moves as the object to be measured moves. When the object to be measured moves within a preset distance range, the first detection unit and the second detection unit form a coupling capacitor.

[0007] In one embodiment, the first detection unit includes a first sensing electrode, and the second detection unit includes a second sensing electrode.

[0008] In one embodiment, the pulse input unit includes a first resistor, a second resistor, a first diode, a second diode and a first capacitor, the first end of the first resistor is connected to the cathode of the first diode and connected to the pulse signal, the second end of the first resistor is respectively connected to the first end of the second resistor, the anode of the first diode and the anode of the second diode, the second end of the second resistor is respectively connected to the cathode of the second diode and the first end of the first capacitor, and the second end of the first capacitor is grounded.

[0009] In one embodiment, the sampling module includes a third resistor, a first end of the third resistor is connected to the distance sensing module, and a second end of the third resistor is connected to the comparison module.

[0010] In one embodiment, the comparison module includes a threshold input unit for providing a reference threshold signal; a comparison unit, connected to the threshold input unit and the sampling module, respectively, for obtaining the reference threshold signal and the first voltage signal, outputting a conduction signal when the first voltage signal is greater than or equal to the reference threshold signal, and outputting a cutoff signal when the first voltage signal is less than the reference threshold signal; an output unit, connected to the comparison unit, for outputting a working signal according to the conduction signal, and outputting a shutdown signal according to the cutoff signal.

[0011] In one embodiment, the threshold input unit includes a fourth resistor, a fifth resistor and a second capacitor, the first end of the fourth resistor is connected to a voltage source, the second end of the fourth resistor is respectively connected to the first end of the fifth resistor, the first end of the second capacitor and the comparison unit, and the second end of the fifth resistor and the second end of the second capacitor are grounded.

[0012] In one embodiment, the comparison unit includes a comparator, a first input terminal of the comparator is connected to a reference threshold signal, and a second input terminal of the comparator is connected to the sampling module.

[0013] In one embodiment, the output unit includes a first transistor and a sixth resistor, the gate of the first transistor is connected to the comparison unit, the first electrode of the first transistor is connected to the working voltage signal, the second electrode of the first transistor is connected to the first end of the sixth resistor, the second end of the sixth resistor is grounded, and the connection point between the second electrode of the first transistor and the first end of the sixth resistor serves as the output end of the output unit.

[0014] The above-mentioned limit detection circuit uses the distance sensing module to output a first voltage signal when the object under test moves to a preset distance range, and the sampling module can sample the first voltage signal. The comparison module can determine whether the object under test exceeds the limit position based on the reference threshold signal and the first voltage signal, and output a working signal or a shutdown signal according to the judgment result. By using the limit detection circuit to detect and limit the moving distance of the object under test, contactless limit control of the object under test can be achieved, which solves the problem that the mechanical limit structure may be damaged by contact and collision with the object under test. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the implementation methods of this specification or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0016] Figure 1 This is a schematic diagram of the structure of a limit detection circuit in one of the embodiments of the present application;

[0017] Figure 2 This is a schematic diagram of the positions of the first detection unit and the second detection unit in one embodiment of the present application;

[0018] Figure 3 This is a circuit diagram of a limit detection circuit in one of the embodiments of the present application;

[0019] Figure 4 Schematic diagram of a circuit of a limit detection circuit in another embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to understand the disclosure of the present invention more thoroughly and comprehensively.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0022] Figure 1 1 is a schematic diagram of the structure of a position limit detection circuit in one embodiment of the present application. In one embodiment, the position limit detection circuit may include a distance sensing module 100, a sampling module 200 and a comparison module 300.

[0023] The distance sensing module 100 can be used to output a first voltage signal when the object 10 to be measured moves within a preset distance range. Specifically, the distance sensing module 100 can adjust the preset distance range in advance by means of a program or hardware setting. The preset distance range can be an area close to the distance sensing module 100. For example, an area 0-5 cm away from the distance sensing module 100 is defined as a preset distance range. When applied to a chest compression machine, when a limit detection circuit is used to implement limit detection of a pressing head, a preset distance range can be designed according to the limit moving distance of the pressing head. In this embodiment, the object 10 to be measured can be a pressing head or other moving mechanism in a chest compression machine, and the object 10 to be measured can also be a human body. When the object 10 to be measured moves within the preset distance range, the distance sensing module 100 can sense the distance between the object 10 to be measured and the distance sensing module 100 and output a first voltage signal.

[0024] The sampling module 200 can be connected to the distance sensing module 100, and can be used to sample the first voltage signal. Specifically, after the distance sensing module 100 outputs the first voltage signal when the object 10 moves to a preset distance range, the sampling module 200 can accurately measure the first voltage signal.

[0025] The comparison module 300 can be connected to the sampling module 200, and the comparison module 300 can be used to obtain a reference threshold signal and a first voltage signal. The comparison module 300 can also output a working signal or a closing signal according to the reference threshold signal and the first voltage signal. Specifically, the reference threshold signal obtained by the comparison module 300 can be preset. The comparison module 300 can determine whether the object 10 under test has moved to the limit moving distance by comparing the reference threshold signal and the first voltage signal. When the comparison module 300 determines that the object 10 under test has not moved to the limit moving distance, the comparison module 300 can output a working signal; when the comparison module 300 determines that the object 10 under test has moved to the limit moving distance, the comparison module 300 can output a closing signal.

[0026] The chest compression machine can achieve position limiting according to the working signal or the closing signal output by the comparison module 300. For example, the pressing head of the chest compression machine performs reciprocating telescopic motion, and the extension and retraction of the pressing head can be controlled by the motor encoder and the displacement sensor. The working signal or the closing signal output by the comparison module 300 can be used as a control signal of the motor encoder and / or the displacement sensor. The motor encoder and / or the displacement sensor controls the pressing head to continue to move according to the working signal, and controls the pressing head to stop moving according to the closing signal, so as to prevent the chest compression machine from exceeding the limit position.

[0027] The above-mentioned limit detection circuit uses the distance sensing module 100 to output a first voltage signal when the measured object 10 moves to a preset distance range, and the sampling module 200 samples the first voltage signal. The comparison module 300 determines whether the measured object 10 exceeds the limit position based on the reference threshold signal and the first voltage signal, and outputs a working signal or a shutdown signal according to the judgment result. By using the limit detection circuit to detect and limit the moving distance of the measured object 10, contactless limit control of the measured object 10 can be achieved, which solves the problem that the mechanical limit structure may be damaged by contact and collision with the measured object 10.

[0028] In one embodiment, the distance sensing module 100 may include a first detection unit 110 and a pulse input unit 120 connected to the first detection unit 110. When the object 10 to be detected moves within a preset distance range, the first detection unit 100 may form a coupling capacitor with the object 10 to be detected. The pulse input unit 120 may output a first voltage signal according to the coupling capacitor. The pulse input unit 120 may be connected to a pulse signal, so that different voltage signals are distributed on different devices in the pulse input unit 120.

[0029] When the first detection unit 100 forms a coupling capacitor with the object 10 to be measured, the capacitance distribution in the pulse input unit 120 will be changed, thereby changing the voltage distribution in the pulse input unit 120. At the same time, the closer the distance between the first detection unit 100 and the object 10 to be measured is, the higher the capacitance of the coupling capacitor is, so that the coupling capacitor has a higher degree of influence on the voltage distribution in the pulse input unit 120. In this embodiment, the signal whose voltage changes due to the influence of the coupling capacitor can be defined as a first voltage signal. It can be seen that the comparison module 300 can determine the movement of the object 10 to be measured by analyzing the voltage change of the first voltage signal. When the voltage change amplitude of the first voltage signal is large, the distance between the first detection unit 100 and the object 10 to be measured is close, and when the voltage change amplitude of the first voltage signal is small, the distance between the first detection unit 100 and the object 10 to be measured is far.

[0030] Figure 2This is a schematic diagram of the positions of the first detection unit and the second detection unit in one embodiment of the present application. In one embodiment, the distance sensing module 100 may further include a second detection unit 130. The second detection unit 130 may be disposed on the object 10 to be detected, and the second detection unit 130 may move with the movement of the object 10 to be detected. Preferably, the second detection unit 130 is detachably disposed at the end of the object 10 to be detected close to the first detection unit 110.

[0031] When the object 10 to be detected moves to within the preset distance range, the second detection unit 130 will also move to within the preset distance range along with the movement of the object 10 to be detected, so that a coupling capacitor can be formed between the first detection unit 110 and the second detection unit 120. In this embodiment, when the second detection unit 130 is close to the first detection unit 110, the air can be used as a conductive medium, and the first detection unit 110 and the second detection unit 130 can be used as two ends of the conductive medium to input or output current, respectively, so that a coupling current is formed between the first detection unit 110 and the second detection unit 130.

[0032] In one embodiment, a coupling capacitor may be formed between the first detection unit 110 and the second detection unit 120, and the capacitance value of the coupling capacitor is related to factors such as the distance between the plates and the area of ​​the plates. Therefore, preferably, when the second detection unit 130 moves to a preset distance range with the object 10 to be measured, the first detection unit 110 and the second detection unit 130 remain in a state of relative arrangement, and the size of the first detection unit 110 in the direction of the orthographic projection of the second detection unit 130 remains unchanged. By making the first detection unit 110 and the second detection unit 130 remain in a state of relative arrangement, and the size of the first detection unit 110 in the direction of the orthographic projection of the second detection unit 130 remains unchanged, the influence of other variables on the capacitance value of the coupling capacitor is reduced, and it is ensured that the change in the capacitance value of the coupling capacitor is only related to the distance between the plates (i.e., the distance between the first detection unit 110 and the second detection unit 120).

[0033] In one embodiment, the first detection unit 110 may include a first sensing electrode, and the second detection unit 130 may include a second sensing electrode. At least one of the first sensing electrode and the second sensing electrode is made of a material with good electrical conductivity. For example, the first sensing electrode and the second sensing electrode may be two metal sheets. By using a material with good electrical conductivity to prepare the first sensing electrode and / or the second sensing electrode, the coupling effect between the first sensing electrode and the second sensing electrode can be ensured, thereby improving the stability of the circuit.

[0034] Figure 3This is a circuit diagram of a limit detection circuit in one of the embodiments of the present application. In one of the embodiments, the pulse input unit 120 may include a first resistor R1, a second resistor R2, a first diode D1, a second diode D2 and a first capacitor C1. Figure 3 The middle node A may be a connection point between the second end of the first resistor R1, the first end of the second resistor R2, the anode of the first diode D1 and the anode of the second diode D2, and the node B may be a connection point between the second end of the second resistor R2, the cathode of the second diode D2 and the first end of the first capacitor C1.

[0035] The first end of the first resistor R1 can be connected to the cathode of the first diode D1 and connected to the pulse signal PWM, the second end of the first resistor R1 can be connected to the first end of the second resistor R2, the anode of the first diode D1 and the anode of the second diode D2 respectively, the second end of the second resistor R2 can be connected to the cathode of the second diode D2 and the first end of the first capacitor C1 respectively, and the second end of the first capacitor C1 can be grounded.

[0036] The first end of the first resistor R1 can be connected to a high-frequency pulse signal. Specifically, the first end of the first resistor R1 can be connected to a high-frequency pulse signal by connecting to a high-frequency pulse signal generating circuit. Preferably, the high-frequency pulse signal generating circuit can generate a pulse signal with a frequency of [400,500] kHz, and the voltage amplitude of the high-frequency pulse signal can be 3.3V / 5V. Since the diode has the characteristic of unidirectional conduction, when the input high-frequency pulse signal is in the positive half cycle, the current can be transmitted to the first end of the first capacitor C1 through the first resistor R1 and the second diode D2 in sequence to charge the first capacitor C1. At this time, the charging current I of the first capacitor C1 充 =(VOUT-VC1) / R1, where VOUT is the voltage amplitude of the high-frequency pulse signal, VC1 is the voltage across the first capacitor C1, and R1 is the resistance of the first resistor R1. When the input high-frequency pulse signal is in the negative half cycle, the first capacitor C1 can be discharged through the second resistor R2 and the first diode D1 in sequence, and the discharge current I 放 =VC1 / R2, where VC1 is the voltage across the first capacitor C1, and R2 is the resistance of the first resistor R2.

[0037] When the voltage across the first capacitor C1 is stable, I 充 =I 放 In a preferred embodiment, the first resistor R1 and the second resistor R1 have the same resistance value. Since the first resistor R1 and the second resistor R1 have the same resistance value, VC4=VOUT / 2.

[0038] In one embodiment, the sampling module 200 may include a third resistor R3, a first end of the third resistor R3 may be connected to the distance sensing module 100, and a second end of the third resistor R3 may be connected to the comparison module 300. Specifically, the first end of the third resistor R3 is respectively connected to the second end of the second resistor R2, the cathode of the second diode D2, and the first end of the first capacitor C1. That is, the first end of the third resistor R3 may be connected to the node B, and the third resistor R3 may introduce the signal at the node B into the comparison module 300. In this embodiment, the signal at the node B may be defined as a first voltage signal. The sampling module 200 collects the first voltage signal at the node B and transmits it to the comparison module 300.

[0039] In one embodiment, the first voltage signal can be adjusted by adjusting the resistance of the third resistor R3. Since the voltage value across the third resistor R3 is positively correlated with the resistance of the third resistor R3, when the voltage amplitude of the first voltage signal is too small to be compared, the first voltage signal can be amplified by increasing the resistance of the third resistor R3. In some other embodiments, the first voltage signal can also be amplified by adding an amplification unit.

[0040] In one embodiment, Figure 3 U2 may be a pad connected to the first detection unit 110, and the first detection unit 110 may be connected to the second end of the first resistor R1, the first end of the second resistor R2, the anode of the first diode D1, and the anode of the second diode D2 through the pad U2, that is, the first detection unit 110 may be connected to the node A. When the object 10 to be detected moves within a preset distance range, the object 10 to be detected may form a coupling capacitor with the first detection unit 110, and the coupling capacitor will change the distribution of the capacitance in the pulse input unit 120, which is equivalent to adding a bypass capacitor C at the position of the node A.

[0041] At this time, in the negative half cycle of the high-frequency pulse signal, the bypass capacitor C can be discharged through the first diode D1, so that the voltage on the bypass capacitor C returns to zero. In the positive half cycle of the high-frequency pulse signal, a part of the current that originally only charges the first capacitor C1 will be diverted to charge the bypass capacitor C1, thereby causing the voltage at the node B to drop. That is, when the object 10 to be measured moves to within the preset distance range, the coupling capacitance formed by the object 10 to be measured and the first detection unit 110 will cause the voltage at the node B to drop.

[0042] At the same time, when the distance between the measured object 10 and the first detection unit 110 is shorter, the capacitance of the coupling capacitor formed between the measured object 10 and the first detection unit 110 is larger, then the charging current is diverted more, and the voltage at the node B is smaller. That is, when the measured object 10 is closer to the first detection unit 110, the voltage at the node B is smaller. It can be seen that by sampling the voltage at the node B in real time, the distance between the measured object 10 and the first detection unit 110 can be monitored.

[0043] In one embodiment, the comparison module 300 may include a threshold input unit 310 , a comparison unit 320 , and an output unit 330 .

[0044] The threshold input unit 310 can be used to provide a reference threshold signal. The reference threshold signal can be a signal used to determine whether the distance between the measured object 10 and the first detection unit 110 is a limit distance. In practical applications, the reference threshold signal can be determined based on the first voltage signal when the distance between the first detection unit 110 and the measured object 10 is the limit distance. For example, when the distance between the first detection unit 110 and the measured object 10 is the limit distance of 3 cm, the reference threshold signal can be the same as or related to the first voltage signal when the distance between the first detection unit 110 and the measured object 10 is 3 cm.

[0045] The comparison unit 320 can be connected to the threshold input unit 310 and the sampling module 200 respectively. The comparison unit 320 can obtain the reference threshold signal through the threshold input unit 310 and obtain the first voltage signal through the sampling module 200. The comparison unit 320 can compare the reference threshold signal and the first voltage signal and output a conduction signal or a cutoff signal based on the comparison result. The comparison unit 320 can output a conduction signal when the first voltage signal is greater than or equal to the reference threshold signal, and output a cutoff signal when the first voltage signal is less than the reference threshold signal.

[0046] The output unit 330 may be connected to the comparison unit 320, and the output unit 330 may output a working signal according to the on signal, and output a shut-down signal according to the cut-off signal. That is, the comparison module 300 outputs a working signal when the first voltage signal is greater than or equal to the reference threshold signal, and the comparison module 300 outputs a shut-down signal when the first voltage signal is less than the reference threshold signal.

[0047] In one embodiment, see Figure 3 , the threshold input unit 310 may include a fourth resistor R4, a fifth resistor R5 and a second capacitor C2.

[0048] The first end of the fourth resistor R4 can be connected to a voltage source, and the voltage source can be used to provide a voltage signal to the threshold input unit 310. For example, the voltage source can provide a +5V voltage signal. The second end of the fourth resistor R4 can be connected to the first end of the fifth resistor R5, the first end of the second capacitor C2 and the comparison unit 320, respectively, and the second end of the fifth resistor R5 and the second end of the second capacitor C2 can be grounded. The first end of the fifth resistor R5 is connected to the comparison unit 320, that is, the voltage at the first end of the fifth resistor R5 can be transmitted to the comparison unit 320 as a reference threshold signal. The second capacitor C2 is connected in parallel with the fifth resistor R5, and can be used to maintain the voltage across the fifth resistor R5.

[0049] In some embodiments, the voltage at the first end of the fifth resistor R5 can be adjusted by adjusting the resistance values ​​of the fourth resistor R4 and the fifth resistor R5 , thereby adjusting the voltage of the reference threshold signal transmitted to the comparison unit 320 .

[0050] In one embodiment, see Figure 3 , the comparison unit 320 may include a comparator U1, a first input terminal of the comparator 320 may be connected to a reference threshold signal, and a second input terminal of the comparator 320 may be connected to the sampling module 200. In this embodiment, the comparator U1 may be a voltage comparator, which may be used to determine the voltage value of the reference threshold signal and the voltage value of the first voltage signal. The comparator U1 may have two input terminals and one output terminal, and the two input terminals are respectively a positive input terminal and a negative input terminal. The two input terminals of the comparator U1 are respectively connected to analog signals, and the output terminal outputs a digital signal. The value of the high level outputted by the output terminal of the comparator U1 is determined by the amplitude of the external working voltage of the comparator U1. Figure 3 The comparator U1 is connected to a +5V voltage signal.

[0051] The first input terminal of the comparator U1 may be an inverting input terminal, connected to the threshold input unit 310, and the second input terminal of the comparator U1 may be a non-inverting input terminal, connected to the sampling module 200. Specifically, the first input terminal of the comparator U1 may be connected to the second end of the fourth resistor R4, the first end of the fifth resistor R5, and the first end of the second capacitor C2, respectively, and the second input terminal of the comparator U1 may be connected to the second end of the third resistor.

[0052] In one embodiment, the output unit 330 may include a first transistor Q1 and a sixth resistor R6.

[0053] In the embodiments of the present disclosure, a transistor refers to a component including at least a gate, a drain, and a source. In the present disclosure, the first electrode of the transistor may be a drain, the second electrode may be a source, or the first electrode may be a source, and the second electrode may be a drain. In the case of using transistors with opposite polarities or the current direction changes during circuit operation, the functions of the "source" and "drain" are sometimes interchanged. In the embodiments of the present disclosure, the gates of all or part of the transistors may be used as control electrodes, and the first electrode and the second electrode may be interchangeable as needed.

[0054] In this embodiment, the first transistor Q1 may be an N-type transistor, and the first transistor Q1 may be turned on according to a high level and turned off according to a low level. That is, the turn-on signal is a high level signal, and the turn-off signal is a low level signal. In some other embodiments, the first transistor Q1 may also be a P-type transistor, and the first transistor Q1 may be turned on according to a low level and turned off according to a high level, that is, the turn-on signal is a low level signal, and the turn-off signal is a high level signal.

[0055] The gate of the first transistor Q1 is connected to the comparison unit 320. Specifically, the gate of the first transistor Q1 can be connected to the output end of the comparator U1. The first electrode of the first transistor Q1 can be connected to the working voltage signal, the second electrode of the first transistor Q1 can be connected to the first end of the sixth resistor R6, and the second end of the sixth resistor R6 can be grounded. The connection point between the second electrode of the first transistor Q1 and the first end of the sixth resistor R6 can serve as the output end OUT of the output unit 330.

[0056] In this embodiment, combined with Figure 3 The circuit diagram shown illustrates the working principle of the limit detection circuit, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. Among them, the first transistor Q1 is an N-type transistor, the distance between the measured object 10 and the first detection unit 110 is set to 3 cm, that is, the reference threshold signal is the same as or related to the first voltage signal when the distance between the measured object 10 and the first detection unit 110 is 3 cm, PWM is a pulse signal, OUT is the output end of the comparison module 300, and GND is ground.

[0057] When the object under test 10 has not moved to the preset distance range, when the high-frequency pulse signal connected to the pulse input unit 120 is in the positive half cycle, the current can be transmitted to the first end of the first capacitor C1 through the first resistor R1 and the second diode D2 in sequence to charge the first capacitor C1; when the high-frequency pulse signal is in the negative half cycle, the first capacitor C1 can be discharged through the second resistor R2 and the first diode D1 in sequence.

[0058] When the object 10 moves to a preset distance range, the object 10 can form a coupling capacitor with the first detection unit 110, and the coupling capacitor will change the distribution of the capacitance in the pulse input unit 120, which is equivalent to adding a bypass capacitor C at the node A position.

[0059] At this time, in the negative half cycle of the high-frequency pulse signal, the bypass capacitor C can be discharged through the first diode D1, so that the voltage on the bypass capacitor C returns to zero. In the positive half cycle of the high-frequency pulse signal, a part of the current that originally only charges the first capacitor C1 will be diverted to charge the bypass capacitor C1, thereby causing the voltage at the node B to drop. That is, when the object 10 to be measured moves to within the preset distance range, the coupling capacitance formed by the object 10 to be measured and the first detection unit 110 will cause the voltage at the node B to drop.

[0060] The third resistor R3 can transmit the first voltage signal having a voltage change at the node B to the second input terminal of the comparator U1 . The first input terminal of the comparator U1 is connected to the reference threshold signal.

[0061] The comparator U1 compares the first voltage signal with the reference threshold signal. When the object 10 moves within the preset distance range and the distance between the object 10 and the first detection unit 110 is greater than or equal to 3 cm, the first voltage signal at the node B will be greater than or equal to the reference threshold signal, so that the comparator U1 outputs a high level signal when the first voltage signal is greater than or equal to the reference threshold signal. The high level signal is transmitted to the gate of the first transistor Q1, and the first transistor Q1 can be turned on according to the high level signal, so that the voltage signal provided by the voltage source can be transmitted to the sixth resistor R6, that is, the output terminal OUT of the comparison module 300 can output a working signal.

[0062] When the object 10 moves within the preset distance range and the distance between the object 10 and the first detection unit 110 is less than 3 cm, the first voltage signal at the node B will be less than the reference threshold signal, so that the comparator U1 outputs a low level signal when the first voltage signal is less than the reference threshold signal. The low level signal is transmitted to the gate of the first transistor Q1, and the first transistor Q1 can be cut off according to the low level signal, so that the voltage signal provided by the voltage source cannot be transmitted to the sixth resistor, that is, the output terminal OUT of the comparison module 300 will output a shutdown signal. In this embodiment, the shutdown signal can be 0V.

[0063] In one embodiment, the operating voltage signal transmitted to the first transistor Q1 can be adjusted by adjusting the circuit connected to the first electrode of the first transistor Q1. Figure 3As shown, the first electrode of the first transistor Q1 is connected to the first end of the seventh resistor R7, and the second end of the seventh resistor R7 is connected to the voltage source. The voltage source can be used to provide a voltage signal to the first transistor Q1. For example, Figure 3 The medium voltage source provides a +5V voltage signal, the resistance of the seventh resistor R7 is 0Ω, and the voltage at the first end of the sixth resistor R6 is 5V. Therefore, the working signal output by the comparison module 300 can be a 5V voltage signal.

[0064] Figure 4 This is a circuit diagram of a limit detection circuit in another embodiment of the present application. In one embodiment, the first electrode of the first transistor Q1 is connected to the first end of the eighth resistor R8 and the first end of the ninth resistor R9 respectively, the second end of the eighth resistor R8 is connected to the voltage source, and the second end of the ninth resistor R9 is grounded. By adjusting the resistance values ​​of the eighth resistor R8, the ninth resistor R9 and the sixth resistor R6, the working signal of the output terminal OUT of the comparison module 300 can be adjusted. For example, Figure 4 The medium voltage source provides a +5V voltage signal, the resistance of the eighth resistor R8 is 1.7kΩ, the resistance of the ninth resistor R9 is 3.3kΩ, and the resistance of the sixth resistor R6 is 200Ω. The voltage at the first end of the sixth resistor R6 is 3.3V, so the working signal output by the comparison module 300 can be a 3.3V voltage signal.

[0065] By using the limit detection circuit provided in the present application, it is possible to realize the limit detection of the object 10 under test without physical contact with the object 10 under test. Furthermore, the limit control of the object 10 under test can be realized based on the limit detection result. It can be seen that the problem that the existing mechanical limit structure may be damaged by contact and collision with the object 10 under test is solved, thereby improving the service life of the product. At the same time, the limit detection circuit in the present application can realize the limit detection of the object 10 under test by using the first detection unit 110 and / or the second detection unit 130 with a smaller volume. At the same time, the limit detection circuit can also be integrated into the existing circuit board in the chest compression machine. It can be seen that the above-mentioned limit detection circuit occupies a small space. Compared with the solution of realizing the limit by using a laser limit sensor in the prior art, the space occupied by the limit detection circuit in the present application is very small, which is conducive to the improvement and upgrading of the product and reduces the production cost of the product.

[0066] It is understandable that the various embodiments of the above method in this specification are described in a progressive manner, and the same / similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. For related parts, refer to the description of other method embodiments.

[0067] In the description of this specification, the descriptions with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc., mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the utility model. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0068] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A limit detection circuit, characterized in that: include: A distance sensing module, configured to output a first voltage signal when the object under test moves within a preset distance range; a sampling module, connected to the distance sensing module, and configured to sample the first voltage signal; A comparison module is connected to the sampling module, and is used to obtain a reference threshold signal and the first voltage signal, and output a working signal or a shut-down signal according to the reference threshold signal and the first voltage signal.

2. The limit detection circuit according to claim 1, characterized in that: The distance sensing module includes a first detection unit and a pulse input unit connected to the first detection unit. When the object to be measured moves within a preset distance range, the first detection unit forms a coupling capacitor with the object to be measured; The pulse input unit outputs a first voltage signal according to the coupling capacitor.

3. The limit detection circuit according to claim 2, characterized in that: The distance sensing module also includes a second detection unit, which is disposed on the object to be measured and moves with the movement of the object to be measured. When the object to be measured moves within a preset distance range, the first detection unit and the second detection unit form a coupling capacitor.

4. The limit detection circuit according to claim 3, characterized in that: The first detection unit includes a first sensing electrode, and the second detection unit includes a second sensing electrode.

5. The limit detection circuit according to claim 2, characterized in that: The pulse input unit includes a first resistor, a second resistor, a first diode, a second diode and a first capacitor. The first end of the first resistor is connected to the cathode of the first diode and connected to the pulse signal, the second end of the first resistor is respectively connected to the first end of the second resistor, the anode of the first diode and the anode of the second diode, the second end of the second resistor is respectively connected to the cathode of the second diode and the first end of the first capacitor, and the second end of the first capacitor is grounded.

6. The limit detection circuit according to claim 1 or 2, characterized in that: The sampling module includes a third resistor, a first end of the third resistor is connected to the distance sensing module, and a second end of the third resistor is connected to the comparison module.

7. The limit detection circuit according to claim 6, characterized in that: The comparison module comprises: A threshold input unit, used for providing a reference threshold signal; a comparison unit, connected to the threshold input unit and the sampling module respectively, for obtaining a reference threshold signal and the first voltage signal, outputting an on signal when the first voltage signal is greater than or equal to the reference threshold signal, and outputting an off signal when the first voltage signal is less than the reference threshold signal; An output unit is connected to the comparison unit and is used to output a working signal according to the conduction signal and to output a shutdown signal according to the cut-off signal.

8. The limit detection circuit according to claim 7, characterized in that: The threshold input unit includes a fourth resistor, a fifth resistor and a second capacitor, The first end of the fourth resistor is connected to a voltage source, the second end of the fourth resistor is respectively connected to the first end of the fifth resistor, the first end of the second capacitor and the comparison unit, and the second end of the fifth resistor and the second end of the second capacitor are grounded.

9. The limit detection circuit according to claim 7, characterized in that: The comparison unit comprises a comparator, a first input terminal of the comparator is connected to a reference threshold signal, and a second input terminal of the comparator is connected to the sampling module.

10. The limit detection circuit according to claim 7, characterized in that: The output unit includes a first transistor and a sixth resistor, the gate of the first transistor is connected to the comparison unit, the first electrode of the first transistor is connected to the working voltage signal, the second electrode of the first transistor is connected to the first end of the sixth resistor, the second end of the sixth resistor is grounded, and the connection point between the second electrode of the first transistor and the first end of the sixth resistor serves as the output end of the output unit.

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