Short circuit protection and electrode off detection method for an electrical stimulator

Abstract

The application discloses a short-circuit protection and electrode off detection method of an electric stimulator, and relates to the technical field of medical devices.A short-circuit protection circuit monitors the level change of a load end in real time through a sampling resistor and a trigger chip connected in series in an output loop; during normal operation, an output pulse continuously clears a counter of the trigger chip; when a short circuit occurs, the pulse disappears, the counter of the trigger chip overflows, and the MCU is triggered to alarm and shut down the output; an electrode off detection circuit adopts a segmented detection strategy for an H-bridge output structure: when a small current flows, the electrode off is determined by detecting the level jump of the voltage across the load; when a large current flows, the electrode off is determined by whether the current detection chip has pulse output.The short-circuit protection is applicable to any output mode, and the electrode off detection circuit is not limited by the size of the output current, so that the safety and reliability of the electric stimulator are improved.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a method for short-circuit protection and electrode detachment detection of an electrical stimulator. Background Technology

[0002] With the rapid development of the medical device field, devices based on electrostimulation technology are widely used in surgical monitoring, rehabilitation therapy, and other fields. Existing electrostimulators, such as neurophysiological systems, peripheral nerve stimulators, and intermediate frequency therapy devices, output bipolar stimulation pulses in various ways, including transformer output, DAC and operational amplifier combination, H-bridge output, and OTL circuits.

[0003] However, these devices have two major drawbacks in use: First, the output terminal may be accidentally short-circuited. If the short circuit lasts for a long time, it will burn out the output drive circuit and damage the equipment. Especially when the output current is low, the short circuit protection function of some devices may not work or may not be able to monitor effectively.

[0004] Secondly, the electrode needles connected to the human body may detach, affecting treatment effectiveness or leading to incorrect monitoring / diagnosis. Current electrode detachment detection methods mostly use optocouplers. Below 1mA, the internal LED of the optocoupler emits weak light, resulting in only weak conduction or no conduction at the output. Typically, the internal LED of the optocoupler requires 3mA to 5mA of current to function properly at the output. Therefore, the detection function fails at low current output.

[0005] To address the aforementioned problems, a short-circuit protection and electrode detachment detection method for electrical stimulators is proposed to solve the problems existing in the prior art, which is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a short-circuit protection and electrode detachment detection method for an electrical stimulator, which can reliably detect short circuits and electrode detachment under both low and high current output conditions, thereby protecting the equipment and ensuring the therapeutic effect.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for short-circuit protection and electrode detachment detection of an electrical stimulator includes the following steps: The short-circuit protection method is applicable to all types of electrical stimulators with different output modes. It collects the voltage change across the load in real time through a sampling resistor network connected in series in the stimulator's output circuit. It uses a comparator chip and a trigger chip to monitor the level change pulse. When no pulse signal is detected, it is determined to be a short circuit and triggers an alarm and output shutdown. Furthermore, the electrode detachment detection method is applicable to electrostimulators that use H-bridge circuits as the output stage. The detection is performed in segments based on the magnitude of the output current: when the output current is less than a preset threshold, the voltage follower monitors the level change across the load terminals to determine detachment; when the output current is greater than or equal to the preset threshold, the absence of the output pulse signal from the current detection chip determines detachment.

[0008] The above methods, optionally, include the following short-circuit protection methods: The first sampling resistor, the second sampling resistor, and the third sampling resistor are connected in series and then connected across the two output terminals of the electrical stimulator. Connect the two input terminals of the comparator chip to the connection point of the first sampling resistor and the second sampling resistor, and the connection point of the second sampling resistor and the third sampling resistor, respectively. Connect the output of the comparator chip to the input of the trigger chip, and connect the output of the trigger chip to the MCU module. During normal output, the comparator chip outputs a pulse signal, triggering the chip counter to be continuously cleared to zero; when the output is short-circuited, the pulse signal disappears, triggering the chip counter to overflow and send an interrupt signal to the MCU. The MCU module then shuts down the output and drives the alarm device.

[0009] The above methods, optionally, include low-current electrode detachment detection methods with an output current of less than 5mA, such as: The fourth and fifth sampling resistors are connected in series and then connected across one output terminal of the electrical stimulator to ground. Connect the input of the voltage follower to the junction of the fourth and fifth sampling resistors, and connect its output to the MCU module. During normal connection, the voltage drop across the load is lower than the TTL high-level threshold, and the MCU module detects it as low level. After the electrode falls off, the BOOST voltage of the boost circuit is output from the H-bridge output terminal. After being divided by the fourth and fifth sampling resistors, it is higher than the TTL high-level threshold. The MCU module detects the level change, shuts off the output, and alarms.

[0010] The above methods, optionally, include low-current electrode detachment detection methods with an output current of 5mA or higher, such as: The current detection chip is connected in series with the output circuit of the electrical stimulator, and its output terminal is connected to the MCU module. When connected normally, the output current flows through the current detection chip, and its output terminal sends periodic pulses to the MCU module, continuously resetting the internal counter of the MCU module to zero; after the electrode falls off, the circuit is broken, the pulse signal output by the current detection chip cannot be detected, the MCU module counter overflows, shuts off the output, and alarms.

[0011] Optionally, the alarm device includes a buzzer and its driving circuit. The driving circuit is composed of a transistor controlled by an MCU module, and the buzzer is connected in parallel with a freewheeling diode.

[0012] Optionally, the preset threshold for the small current in the above method is 5mA.

[0013] In the above method, optionally, the current detection chip is an optocoupler or a solid-state device with a current transfer ratio.

[0014] Optionally, the alarm device may also include a light-emitting diode flashing indicator circuit controlled by an MCU module.

[0015] Optionally, the output terminal of the electrical stimulator is equipped with a short-circuit protection circuit and an electrode detachment detection circuit. The electrode detachment detection circuit includes a low-current detection branch and a high-current detection branch, and switches the detection branch according to a preset current threshold.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention provides a short-circuit protection and electrode detachment detection method for an electrical stimulator, which has the following beneficial effects: (1) The short circuit protection is not affected by the output current and can effectively detect short circuit conditions, including small signals, to avoid equipment damage; (2) Electrode detachment detection solves the problem of failure of traditional optocoupler schemes under low current, and realizes reliable detection across the entire current range; (3) Short circuit detection uses an independent trigger chip, which reduces the burden on the MCU module and improves the system response speed; (4) The electrode detachment detection is designed in segments so that they do not interfere with each other. After long-term verification, it reduces the risk of misjudgment by users. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a block diagram illustrating the application of the short-circuit protection and electrode detachment detection circuit of the present invention in a product. Figure 2 This is a schematic diagram of the short-circuit protection circuit disclosed in this invention; Figure 3 This is a schematic diagram of the overall principle of the electrode detachment detection scheme disclosed in this invention; Figure 4This is a schematic diagram of the current flow direction during normal output of the H-bridge disclosed in this invention; Figure 5 This is a schematic diagram of the output state when the H-bridge electrode detaches, as disclosed in this invention. Figure 6 This is an internal schematic diagram of a current detection chip in the prior art. Figure 7 This is an internal schematic diagram of another current detection chip in the prior art; Figure 8 This is an internal schematic diagram of another type of optocoupler current detection in the prior art; Figure 9 for Figure 8 Forward voltage drop and forward current curves of the optocoupler. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0021] This invention adds an output short-circuit protection and alarm circuit, and an electrode detachment detection circuit to the basic neuromuscular stimulator. It primarily addresses the common problems in existing stimulators on the market, such as damage caused by output short circuits and the failure of users to promptly detect accidental electrode detachment during normal use.

[0022] This invention significantly improves the self-protection performance of neuromuscular stimulators in the event of an accidental short circuit during use, avoiding the risk of device damage due to such a short circuit. When the electrode detachment detection circuit detects electrode detachment, the stimulator shuts off invalid outputs, ensuring that the treatment signal is effectively applied to the body. Simultaneously, it reduces the probability of user misjudgment.

[0023] The solution proposes a real-time short-circuit monitoring method, aiming to promptly cut off the output of the electrode and issue an alarm when a short circuit is present at the output electrode, reminding users to handle the situation in a timely manner. The application block diagram of the solution in the product is shown below. Figure 1 As shown, this system can detect short circuits at the load end in real time and provide an alarm signal. Furthermore, this solution is applicable to short circuit protection for any bipolar pulse output. Detailed schematic diagram is shown below. Figure 2 As shown.

[0024] It should be noted that the electrode detachment detection circuit is as follows: The electrode detachment protection scheme is only applicable to electrical stimulators that use H-bridge circuits as the constant current method.

[0025] The electrode detachment detection circuit in this invention aims to detect situations where electrodes accidentally detach during normal use of the stimulator without the user's notice, thus preventing misjudgment of treatment results. The detection principle of this invention is achieved by detecting the current path. Although related current detection chips exist on the market, they all have drawbacks for current detection in neuromuscular stimulators, as detailed below: See Figure 6 The diagram shows the internal schematic of a commercially available current sensing chip, which contains a resistor network. When the chip's IN- / IN+ pins are connected to the sensing resistor, a voltage difference exists between IN- / IN+ during normal operation of the neuromuscular stimulator, resulting in a corresponding comparison signal output at the chip's OUT terminal. When electrode detachment occurs, the neuromuscular stimulator outputs positive and negative pulses of the same frequency and pulse width as the control pulse signal, equal to the BOOST voltage. This voltage forms a loop through the sensing resistor and the internal resistor network of the current sensing chip, resulting in a signal output at the chip's OUT terminal, thus making it impossible to distinguish whether electrode detachment has occurred. Even when electrode detachment occurs, a current I2 still flows through the sensing resistor.

[0026] See Figure 7The diagram shows the schematic of another current sensing chip on the market, which does not have an internal resistor network. When the neurostimulator is working normally, there is a voltage difference across the sampling resistor Rs. The comparator compares this input voltage difference and outputs a voltage. This voltage turns on the internal MOSFET. When no current flows through the sampling resistor Rs, the voltage difference across it is zero. However, due to the offset voltage of the internal comparator, there will still be a voltage output at the comparator's output, which can turn on the internal MOSFET. Therefore, the internal MOSFET will be turned on regardless of whether the electrode is dislodged. This makes it impossible to accurately detect the current path.

[0027] See Figure 8 As shown, one existing solution uses optocoupler current detection, with the input terminal of the optocoupler connected in series with the output circuit. When there is current in the circuit, the output terminal (OUT terminal) of the optocoupler will output a signal. If the circuit is open, and there is no current in the output circuit, the output terminal of the optocoupler will not output a signal. This solution is theoretically feasible. However, from... Figure 9 It can be seen that the current transfer ratio is only slightly over 70% when the input current is 1mA. Considering the aging and light decay of the internal LEDs of the optocoupler during use, the actual current transfer ratio is lower than 70%. Figure 9 The current transfer ratio for input currents less than 1mA is not given, indicating that an input current less than 1mA is insufficient to turn on the output, or the output will only conduct weakly. A weak output signal cannot be provided. Therefore, if a reliable output signal is required, the optocoupler input current must be at least 3mA or 5mA for detection to be possible.

[0028] To address the above situation, the inventors proposed a method for detecting electrode detachment in neuromuscular stimulators, see [link to relevant documentation]. Figure 3 The purpose is to detect situations where electrodes of a stimulator accidentally detach during normal use without the user noticing, thus avoiding misjudgments of treatment results by the user.

[0029] The specific technical solution of this invention is as follows: See Figure 2 and Figure 3 As shown, this invention discloses a short-circuit protection and electrode detachment detection method for an electrical stimulator, comprising the following steps: The short-circuit protection method is applicable to all output types of electrical stimulators. It collects the voltage change across the load resistor R1 in real time through a sampling resistor network connected in series in the stimulator output circuit. The comparator chip U2 and the trigger chip U3 are used to monitor the level change pulse. When no pulse is detected, it is determined to be a short circuit and triggers an alarm and output shutdown. Furthermore, the electrode detachment detection method is applicable to electrical stimulators that use H-bridge circuits as the output stage. The detection is performed in segments based on the magnitude of the output current: when the output current is less than a preset threshold, the voltage follower U6 monitors the level transitions at both ends of the load to determine detachment; when the output current is greater than or equal to the preset threshold, the output pulse signal of the current detection chip U5 is not detected to determine detachment.

[0030] Further, see Figure 2 As shown, short-circuit protection methods include: The first sampling resistor R2, the second sampling resistor R3, and the third sampling resistor R4 are connected in series and then connected across the two output terminals of the electrical stimulator. Connect the two input terminals of comparator chip U2 to the connection point of the first sampling resistor R2 and the second sampling resistor R3, and the connection point of the second sampling resistor R3 and the third sampling resistor R4, respectively. Connect the output of comparator chip U2 to the input of trigger chip U3, and connect the output of trigger chip U3 to MCU module U1; During normal output, comparator chip U2 outputs a pulse signal, triggering chip U3's counter to be continuously cleared to zero; when the output is short-circuited, no pulse signal is detected, triggering chip U3's counter to overflow and send an interrupt signal to MCU module U1, which then shuts off the output and drives the alarm device.

[0031] Further, see Figure 3 As shown, the electrode detachment detection method under low current includes: The fourth sampling resistor R11 and the fifth sampling resistor R12 are connected in series and then connected across one of the output terminals of the electrical stimulator to ground; Connect the input terminal of voltage follower U6 to the connection point of the fourth sampling resistor R11 and the fifth sampling resistor R12, and connect its output terminal to MCU module U1. During normal connection, the voltage drop across the load resistor R1 is lower than the TTL high-level threshold, and the MCU module U1 detects a low level. After the electrode falls off, the power supply voltage output at the H-bridge output terminal is higher than the TTL high-level threshold after being divided by the fourth sampling resistor R11 and the fifth sampling resistor R12. The MCU module U1 detects the level change, shuts off the output, and alarms.

[0032] Furthermore, methods for detecting electrode detachment under high current include: The current detection chip U5 is connected in series with the output circuit of the electrical stimulator, and its output terminal is connected to the MCU module U1. During normal connection, the output current flows through the current detection chip U5, and its output terminal sends periodic pulses to the MCU module U1. The internal counter of the MCU module U1 is continuously cleared to zero. After the electrode falls off, the circuit is broken, the pulse is lost, the counter of the MCU module U1 overflows, the output is shut off and an alarm is triggered.

[0033] Furthermore, the alarm device includes a buzzer BEEP1 and its driving circuit. The driving circuit is composed of a first transistor Q1 controlled by the MCU module U1, and a freewheeling diode D1 is connected in parallel with the buzzer BEEP1.

[0034] Furthermore, the preset threshold for low current is 5mA. This detection scheme is divided into electrode detachment detection under low current conditions (5mA), detachment detection under output current conditions (above 5mA), and output alarm indication, based on the output current magnitude.

[0035] Furthermore, the current sensing chip U5 is an optocoupler or a solid-state device with a current transfer ratio.

[0036] Furthermore, the alarm device also includes a flashing indicator circuit for LED D3 controlled by MCU module U1.

[0037] Furthermore, the output terminal of the electrical stimulator is equipped with a short-circuit protection circuit and an electrode detachment detection circuit. The electrode detachment detection circuit includes a low-current detection branch and a high-current detection branch, and switches the detection branch according to a preset current threshold.

[0038] Example 1: Output short-circuit protection and alarm circuit

[0039] like Figure 2 As shown, this embodiment provides a short-circuit monitoring scheme for a neuromuscular stimulator. Circuit connection relationship: One end of the first sampling resistor R2 is connected to one output terminal of the constant voltage / constant current output module 2 (connected to one end of the load), and the other end is connected to the second sampling resistor R3; the other end of the second sampling resistor R3 is connected to the third sampling resistor R4; the other end of the third sampling resistor R4 is connected to the other output terminal of the constant voltage / constant current output module 2 (connected to the other end of the load).

[0040] Pin 2 of comparator chip U2 is connected to the junction of the first sampling resistor R2 and the second sampling resistor R3. Pin 3 is connected to the junction of the second sampling resistor R3 and the third sampling resistor R4. Pin 4 is grounded, pin 8 is connected to VCC, and pin 1 (output) is connected to pin 1 of transducer chip U3. The first pull-up resistor R5 is connected between pin 1 and pin 8 of comparator chip U2.

[0041] The trigger chip U3 has its pin 2 connected to VCC, pin 4 grounded, and pin 3 (output) connected to the PA14 pin of the MCU module U1.

[0042] Alarm circuit: PB12 pin of MCU module U1 is connected to the base of the first transistor Q1, the emitter of the first transistor Q1 is grounded, the collector of the first transistor Q1 is connected to pin 2 of buzzer BEEP1; pin 1 of buzzer BEEP1 is connected to VCC; the cathode of freewheeling diode D1 is connected to VCC, and the anode of freewheeling diode D1 is connected to pin 3 of BEEP1; the first pull-down resistor R6 is connected between the base of the first transistor Q1 and ground.

[0043] Working principle: When the neuromuscular stimulator is working normally, the output pulse signal generates a voltage divider across the first sampling resistor R2, the second sampling resistor R3, and the third sampling resistor R4. Comparator chip U2 detects the change in input voltage difference and outputs a TTL level square wave at its output terminal (pin 1). This square wave is input to trigger chip U3. Upon receiving the rising edge of the square wave, trigger chip U3 continuously clears its internal counter, thus preventing the counter from overflowing. Therefore, there is no trigger signal sent to the MCU module U1 at the output terminal (pin 3) of trigger chip U3.

[0044] When a short circuit occurs at the load end (such as across the load resistor R1), the voltage across the first sampling resistor R2, the second sampling resistor R3, and the third sampling resistor R4 drops to zero. There is no voltage difference at the input of comparator chip U2, and no square wave at the output. The counter inside trigger chip U3 continues counting because it cannot be cleared until it overflows. The overflow signal is sent to MCU module U1 through pin 3 of trigger chip U3. After detecting the trigger signal, MCU module U1 enters the interrupt handler: it immediately shuts down the constant voltage / constant current output module 2 and controls the first transistor Q1 to conduct via pin PB12, driving buzzer BEEP1 to emit an alarm sound. Freewheeling diode D1 is used to absorb the reverse electromotive force when buzzer BEEP1 is de-energized.

[0045] In this scheme, the output of comparator chip U2 is not directly fed into MCU module U1. Instead, it generates an interrupt by triggering the counter overflow mechanism of chip U3, which greatly reduces the software burden of MCU module U1, allowing MCU module U1 to focus more on other tasks. The first sampling resistor R2, the second sampling resistor R3, and the third sampling resistor R4 in the voltage divider resistor network ensure that the signal input to comparator chip U2 is always within its common-mode input range, improving reliability and enabling the detection of short circuits under small signal output.

[0046] Example 2: Electrode detachment detection circuit

[0047] like Figure 3 As shown, this embodiment is for an electrical stimulator with H-bridge output mode, and the detection is performed in segments according to the magnitude of the output current.

[0048] (a) Output indication

[0049] The first current-limiting resistor R14 is connected to a 3.3V power supply at one end and to an LED D3 at the other end. The other end of LED D3 is connected to the collector of the second transistor Q2. The emitter of the second transistor Q2 is grounded. The base of the second transistor is connected to pin PB10 of the MCU module U1. The second pull-down resistor R13 is connected between the base of the second transistor Q2 and ground.

[0050] Working principle: When the PB10 pin of MCU module U1 outputs a high level, the second transistor Q2 is turned on, and the light-emitting diode D3 is lit.

[0051] When the PB10 pin of MCU module U1 outputs a low level, the second transistor Q2 is cut off, and the LED D3 is off. The function of the second pull-down resistor R13 is to reliably pull the base of the second transistor Q2 to ground when the PB10 pin of MCU module U1 outputs a low level.

[0052] (II) Low current output (below 5mA) disconnection detection: The circuit consists of an MCU module U1, a voltage follower U6, a fourth sampling resistor R11, and a fifth sampling resistor R12. One end of the fourth sampling resistor R11 is connected to an output terminal of the constant voltage / constant current output module 2, and the other end is connected to the fifth sampling resistor R12, the other end of which is grounded. The input terminal of the voltage follower U6 is connected to the junction of the fourth and fifth sampling resistors R11 and R12, and the output terminal is connected to the PB12 pin of the MCU module U1.

[0053] Principle: When normally connected to a human body (load approximately 1KΩ), the output current is small, and the voltage across the load is low (e.g., 0.5V). After voltage division by the fourth sampling resistor R11 and the fifth sampling resistor R12, the voltage is far below the TTL high-level threshold, and the PB12 pin of the MCU module U1 is at a low level. The PB10 pin of the MCU module U1 controls the second transistor Q2 to turn on / off, controlling the LED D3 to blink.

[0054] When the electrode detaches, the load becomes infinite. In constant current output mode, theoretically, the output voltage should approach infinity, but in practice, it is limited by the maximum output voltage of the boost circuit, which is defined as the boost voltage. At this time, the boost voltage is divided by the fourth sampling resistor R11 and the fifth sampling resistor R12 and then input to the voltage follower U6, whose output voltage is higher than the TTL high-level threshold. The MCU module U1 detects the change in level from low to high on the PB12 pin, immediately shuts down the output module, and controls the second transistor Q2 to turn on / off through the PB10 pin, driving the LED D3 to flash rapidly several times before turning off for visual alarm. The function of the voltage divider between the fourth sampling resistor R11 and the fifth sampling resistor R12 is to prevent the high voltage under no-load conditions from damaging the input terminal of the voltage follower U6.

[0055] (III) High current output (5mA and above) disconnection test: The circuit consists of a current sensing chip U5 (e.g., an optocoupler with an appropriate current transfer ratio), a second pull-up resistor R7, and a freewheeling diode D2. The input side of U5 is connected in series with the output circuit, and its output side pin 4 is connected to the PD2 pin of MCU module U1 and pulled up to the power supply through the second pull-up resistor R7.

[0056] Principle: During normal connection, the output current flows through the input side of the current detection chip U5. The output side of the current detection chip U5 generates a pulse signal. In the interrupt service routine on the PD2 pin, the MCU module U1 continuously resets its internal counter, preventing the counter from overflowing. At this time, pin PB10 of the MCU module U1 controls the second transistor Q2 to turn on / off, controlling the LED D3 to blink.

[0057] When the electrode detaches, the output circuit is broken, there is no current on the input side of the current detection chip U5, and no pulse on the output side. The internal counter of the MCU module U1 overflows because it cannot be cleared. The overflow program shuts down the output module and controls the second transistor Q2 to turn on / off through pin PB10, driving the LED D3 to flash rapidly several times before turning off for visual alarm.

[0058] When outputting high current, although the voltage follower U6 output will also have a level change, the MCU module U1 will only detect the signal from the current detection chip U5 according to the set current threshold (determined by software), and the two will not interfere with each other.

[0059] For the mechanism by which the output becomes the power supply voltage after electrode detachment, please refer to [link to relevant documentation]. Figure 4 , Figure 5 Including transistors Q11, Q12, Q15, and Q14: During normal operation, transistors Q11 and Q14 are turned on during the positive half-cycle. Transistor Q11 operates in the variable resistance region with extremely low voltage drop, and the voltage at the left end of the load is approximately equal to the highest output voltage of the boost circuit, i.e., the boost voltage. Transistor Q14 operates in constant current mode. Figure 4 After the electrode detaches, the sixth transistor Q14 has no current, and its drain-source voltage drops to 0. Therefore, the voltage at the right end of the load is 0, and the voltage between the left and right ends is the boost voltage. Figure 5 The same applies to the negative half-cycle.

[0060] In summary, this invention, through the cooperation of hardware circuitry and MCU module U1 software strategy, achieves full-range, high-reliability detection of short circuits and electrode detachment in the output of the electrostimulator, significantly improving the safety of the device and the user experience.

[0061] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for short-circuit protection and electrode detachment detection of an electrical stimulator, characterized in that, Includes the following steps: The short-circuit protection method is applicable to all output types of electrical stimulators. It collects the voltage change across the load in real time through a sampling resistor network connected in series in the stimulator output circuit. The comparator chip (U2) and trigger chip (U3) monitor the level change pulse. When no pulse signal is detected, it is determined to be a short circuit and triggers an alarm and output shutdown. Furthermore, the electrode detachment detection method is applicable to electrical stimulators that use H-bridge circuits as the output stage. The detection is performed in segments according to the magnitude of the output current: when the output current is less than a preset threshold, the voltage follower (U6) monitors the level transition across the load to determine detachment; when the output current is greater than or equal to the preset threshold, the detachment is determined by not detecting the output pulse signal of the current detection chip (U5).

2. The method for short-circuit protection and electrode detachment detection of an electrical stimulator according to claim 1, characterized in that, Short circuit protection methods include: The first sampling resistor (R2), the second sampling resistor (R3), and the third sampling resistor (R4) are connected in series and then connected across the two output terminals of the electrical stimulator; Connect the two input terminals of the comparator chip (U2) to the connection point of the first sampling resistor (R2) and the second sampling resistor (R3), and the connection point of the second sampling resistor (R3) and the third sampling resistor (R4), respectively. Connect the output of comparator chip (U2) to the input of trigger chip (U3), and connect the output of trigger chip (U3) to MCU; During normal output, the comparator chip (U2) outputs a pulse signal, which continuously resets the counter of the trigger chip (U3) to zero. When the output is short-circuited, the pulse signal disappears, the counter of the trigger chip overflows, and sends an interrupt signal to the MCU module (U1). The MCU module (U1) then shuts down the output and drives the alarm device.

3. The short-circuit protection and electrode detachment detection method for an electrical stimulator according to claim 2, characterized in that, Methods for detecting electrode detachment with a low current output current of less than 5mA include: The fourth sampling resistor (R11) and the fifth sampling resistor (R12) are connected in series and then connected across one of the output terminals of the electrical stimulator to ground; Connect the input of the voltage follower (U6) to the junction of the fourth sampling resistor (R11) and the fifth sampling resistor (R12), and connect its output to the MCU module (U1). When connected normally, the voltage drop across the load is lower than the TTL high-level threshold, and the MCU module (U1) detects it as low level. After the electrode falls off, the output of the H-bridge outputs the BOOST voltage of the boost circuit. After being divided by the fourth sampling resistor (R11) and the fifth sampling resistor (R12), the voltage is higher than the TTL high-level threshold. The MCU module (U1) detects the level change, shuts down the output, and alarms.

4. The short-circuit protection and electrode detachment detection method for an electrical stimulator according to claim 3, characterized in that, Electrode detachment detection methods under high current conditions of 5mA and above include: The current detection chip (U5) is connected in series in the output circuit of the electrical stimulator, and its output terminal is connected to the MCU module (U1). When connected normally, the output current flows through the current detection chip (U5), and its output terminal sends periodic pulses to the MCU module (U1). The internal counter of the MCU module (U1) is continuously cleared to zero. After the electrode falls off, the circuit is broken, the pulse signal output by the current detection chip (U5) cannot be detected, the counter of the MCU module (U1) overflows, the output is turned off and an alarm is triggered.

5. The short-circuit protection and electrode detachment detection method for an electrical stimulator according to claim 4, characterized in that, The alarm device includes a buzzer (BEEP1) and its driving circuit. The driving circuit is composed of a transistor (Q1) controlled by an MCU module (U1), and the buzzer is connected in parallel with a freewheeling diode (D1).

6. The short-circuit protection and electrode detachment detection method for an electrical stimulator according to claim 5, characterized in that, The preset threshold for low current is 5mA.

7. The short-circuit protection and electrode detachment detection method for an electrical stimulator according to claim 6, characterized in that, The current sensing chip (U5) is an optocoupler or a solid-state device with a current transfer ratio.

8. The short-circuit protection and electrode detachment detection method for an electrical stimulator according to claim 7, characterized in that, The alarm device also includes a flashing indicator circuit for a light-emitting diode (D3) controlled by an MCU module (U1).

9. The short-circuit protection and electrode detachment detection method for an electrical stimulator according to claim 8, characterized in that, The output terminal of the electrical stimulator is equipped with a short-circuit protection circuit and an electrode detachment detection circuit. The electrode detachment detection circuit includes a low-current detection branch and a high-current detection branch, and switches the detection branch according to a preset current threshold.

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