Working principle of low frequency therapeutic instrument
KPM-0 1 Low frequency therapeutic instrument is a portable therapeutic instrument suitable for family health care. The therapeutic principle of the therapeutic instrument is to simulate acupuncture therapy, which has a certain effect on treating scapulohumeral periarthritis, lumbago, muscle sprain, relieving pain and promoting blood circulation.
KPM-0 1 low frequency therapeutic instrument adopts pocket portable structure. The power supply is 4 1.5V batteries, and the housing is provided with a power switch, an output pulse frequency adjustment knob (adjustment range: 2 ~ 13Hz), an amplitude adjustment knob (maximum pulse amplitude is about 100V) and an output connecting wire. The two ends of the wire are respectively welded with circular electrodes. When in use, the two electrodes are symmetrically attached to the skin on both sides of the affected part of the human body with the adhesive tape. In addition, the therapeutic instrument also has the function of delaying the output of electric pulses after starting and automatically shutting down after 30 minutes.
Fig. 29 is the electrical schematic diagram of KPM-0 1 low frequency therapeutic instrument. The therapeutic instrument is mainly composed of three CMOS integrated circuits, which constitute a low-frequency therapeutic pulse generation and output circuit, a start-up delay output circuit and a 30-minute timed automatic shutdown circuit.
The low-frequency therapeutic pulse generation and output circuit consists of IC 1: CD 408 1 (42 input and gate integrated circuit), IC 2: CD 4069? Not gates 4 and 5, VT3, VT4, RP 1, RP2, VD 1, VD2, VD4~VD6, inductors L, etc. Among them, the NOT gates 4 and 5 of IC2, R8, R9, RP2 and C3 form a self-excited oscillator. The pulse wave group output by the self-excited oscillator is the low-frequency therapeutic pulse source. Adjusting RP2 can adjust the frequency of therapeutic pulse in the range of 2 ~ 13Hz, and adjusting RP 1 can adjust the voltage amplitude of therapeutic pulse. The pulse wave output by the self-excited oscillator (pin IC2⑧) passes through the RC circuit composed of RP 1, R 1 and C4, and is sent to AND gate 1 and 4 respectively for shaping and amplification. Because the circuit parameter τ=(RP 1+R 1)C4 is much larger than the therapeutic pulse width output by the self-excited oscillator, the circuit belongs to RC difference channel, and the differential pulse width can be changed by adjusting RP 1. By adjusting the pin of RP 1, IC 1③ can output a pulse signal whose pulse width is continuously adjustable from 0 to 3 ms. When the pin of IC 1③ is at the "1" (high) level, VT3 is saturated and turned on. When the pin of IC 1③ is at "0" (low) level, VT3 is turned off. With the on/off of VT3, a therapeutic electric pulse with amplitude ≤ 100V and frequency 2 ~ 13 Hz is generated on the self-induction coil L, which acts on the affected part of the patient through two electrodes, and stimulates nerve fibers with weak pulse current, thus achieving the purpose of dredging meridians and treating diseases. At the same time, the pulses output by IC 1 and AND gate 4 are shaped and amplified by AND gate 2 to drive VT4. When the pin of IC 1④ is at the "1" (high) level, VT4 is turned on, and the LED emits light (the amplitude of the therapeutic pulse voltage changes with the brightness of the LED, and when the brightness is high, the amplitude of the pulse voltage is also high); When the IC 1④ pin is at the "0" (low) level, VT4 is turned off and the LED is turned off. LED synchronously displays the intensity and frequency of therapeutic electric pulse. In practical use, patients can adjust the pulse amplitude and frequency according to their own feelings, and set the positions of RP 1 and RP2.
In order to prevent the treatment pulse amplitude from being too large when RP 1 is inadvertently set at the maximum output position, and the patient can't adapt to the sudden stimulation, a startup delay circuit is specially set in the circuit to ensure that the treatment pulse amplitude can be gradually increased after startup, so that the patient can have a process from weak to strong and gradually adapt. This circuit consists of NOT gate 6, C 1, R2 ~ R6, VT 1, VD 1, VD2, etc. When the power switch is turned off, C 1 is short-circuited instantly, and VD2 is turned on, so that VT 1 is saturated, and the therapeutic pulse output from the pin of IC2⑧ is turned off. Meanwhile, C 1 passes through the bases of R5 and VD2, R4 and VT 1. Shu Shu? Therefore, the differential pulse width at the C 1② pin becomes narrower, and the voltage amplitude of the therapeutic pulse output at both ends of L becomes smaller. With the increase of the charging voltage at both ends of C 1, the charging current becomes smaller, and VT 1 gradually exits the saturation region, which makes the differential pulse width input to IC 1 (②) pin gradually widen, and the pulse voltage amplitude output at both ends of L gradually increases. About 7 seconds after startup, when the voltage across C 1 is charged to a high level amplitude close to the output of IC2 12, VT 1 turns off; The differential pulse whose pulse width is determined by the position of RP 1 is input to the pin of IC 1② with equal amplitude, and the pulse amplitude output at both ends of L also increases to the amplitude determined by the value of RP 1, and the delay operation process ends.
Figure 29
The 30-minute timed automatic shutdown circuit consists of NOT gates 1, 2, 3 and VT2 in IC3 and IC2. IC3(CD4040) is a 12-bit binary serial counter integrated circuit with 12 counting stages, and each stage has an output (Q 1 ~ Q 12). There are also two input terminals, "CP" is the clock pulse input and "Cr" is the clear input. When the "1" level is applied to the "Cr" terminal, all output terminals are at the "0" level. When "Cr" changes to "0" level, the CD4040 counts up by the falling edge of the clock pulse, and the maximum frequency division coefficient is 2 12=4096. In the figure, the output end (Q 12) ① of IC3 12 counter stage controls the opening and closing of VT2. ① The pin outputs "0" level, VT2 is turned on, and IC 1 and IC2 get 6V voltage to work; ① Is the foot at the level of "1"? , VT2 is closed, and IC 1 and IC2 also stop working. When the switch S is closed, C6 is short-circuited instantly, and the pin (clearing terminal) of IC3 1 1 gets the "1" level, and the pin (Q 12) outputs the "0" level, VT2 is turned on, and IC 1 and IC2⑥. After about 30 minutes, the first segment of IC3 turned to "1" level, then VT2 turned off, IC 1 and IC2 stopped working, and there was no therapeutic pulse output at both ends of L, and the primary treatment process ended. At this time, the patient can manually operate the switch S to cut off the power supply. Even if the patient fails to cut off the power supply in time for some reason, the static current of the therapeutic instrument after regular shutdown is only about 3μA, which consumes very little power and is harmless to human body. ?
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