Traditional Chinese Medical X-ray machine fluoroscopy automatic controller (Workshop Practice) — Circuit, Wiring & Debug Guide

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Medical X-ray machine fluoroscopy automatic controllerThe high-voltage primary circuit of medical X-ray machines has traditionally been controlled by a foot switch or hand brake switch. When the doctor performs fluoroscopy on the patient, his hands must operate the relevant buttons of the fluorescent screen and aperture, his eyes must carefully observe the lesions, and his brain must analyze the nature of the lesions based on clinical experience. At the same time, he must pay attention to loosening the foot switch or hand brake switch. Otherwise, if the X-ray machine is continuously loaded for a long time, it will easily exceed the maximum allowable heat capacity and damage or shorten the life of the X-ray machine, which will bring great inconvenience to the doctor's work. The automatic fluoroscopy controller can automate the control process, relieve the mental burden on the radiologist, and extend the service life of the X-ray tube.Figure 32-1 is the automatic control electrical schematic diagram. The automatic control consists of two parts: exposure and intermittent circuits. The power supply is reduced from AC 220V to 38V through transformer T1, and then rectified by a bridge rectifier composed of 2CP25 four tubes (Figure 32-2). In the figure, SB1 is the trigger signal button. A pair of normally open contacts KL3-2 of the KL3 relay are connected in parallel and series with the fluoroscopy foot switch of the X-ray machine to one end of the KM coil of the fluoroscopy contactor (see Figure 32-2). When the KL3 relay is powered on, KM will work and fluoroscopy can be performed.Figure 32-1Working principle of the circuit: Turn on the X-ray machine and place it in the fluoroscopy position. Press SB1 once, and the relay KL1 will be powered on. Its normally open contact KL1-1 will be closed, KL2 will be powered on, and its normally open contact KL2-1 will be closed and self-protecting. At this time, SB1 can be released and relay KL1 is disconnected, but KL2 relies on this self-locking point to take power through R2 to maintain operation. Because KL2-2 is closed and the normally closed contact K2-3 is open, the base of the transistor VT1 obtains forward bias from R3, R4, R5, KL4-3, KL2-2, and VD2 and conducts, and its collector current causes the relay KL3 to close. The normally open contact KL3-2 (in Figure 32-2) is closed, the coil of the fluoroscopy contactor KM is electrically closed, the contacts KM1 and KM2 are closed, the high-voltage primary of the X-ray machine is turned on to emit X-rays, and the fluoroscopy starts. At the same time, the KL4 normally open contact is also closed, and the thyristor VS1 obtains the positive anode voltage through the relay KL4 coil and resistor R8. At this time, the power supply charges capacitor C7 through potentiometer RP1. When the voltage across C7 reaches the peak voltage of the single-junction transistor VT2, the resistance between e-bl of VT2 suddenly becomes smaller. The voltage on C7 discharges to R10 through b1, and a pulse is generated on R10 and applied to the control electrode of the thyristor VS1, causing VS1 to conduct. As a result, KL4 is electrically activated, its normally open contact KL4-2 is closed, and the anode voltage of VS1 is zero and is cut off. The normally closed contacts of KL4-1, KL4-3, and KL4-4 are disconnected, the power supply of KL2 and KL3 is cut off, the KM coil of the fluoroscopy contactor loses power and stops working, the high-voltage primary of the X-ray machine is cut off, and the fluoroscopy is terminated.Since the exposure circuit KL1 is turned on instantaneously and then turned off, its normally closed contact KL1-2 causes the intermittent circuit to obtain voltage. In addition, due to the action of the exposure circuit KL4, its normally open contact KL4-5 closes instantly. KL5 acts instantaneously after receiving the signal, and its normally open contact KL5-1 closes instantly, causing the relay KL6 to close. Transistor VT3 receives a positive pulse and conducts. Relay KL7 receives collector current to operate, and its normally closed contact KL7-2 opens to cut off the power supply of the exposure circuit. The normally open contact of KL7-1 is closed, the thyristor VS2 obtains the forward anode voltage, and the C15 capacitor is charged through R21. When the voltage on C15 rises from 0 to the peak voltage of VT4, the e-b1 time of VT4 The resistance suddenly becomes smaller, C15 discharges to R20 through b1, the VS2 control pole gets the pulse from R20 and turns on, the relay KL8 acts, and VS2 is blocked because the KL8-2 normally open contact closes and gets the negative voltage. The normally closed contacts of KL8-1, KL8-3, and KL8-4 are opened, KL6 and KL7 are powered off, and the normally closed contacts of KL7-2 are restored so that the exposure circuit obtains voltage. At the same time, due to the action of the intermittent circuit KL8, the normally open contact KL8-5 is closed instantly, causing KL2 to close, the exposure circuit obtains the trigger signal and works, the high-voltage primary circuit of the X-ray machine is connected again, and fluoroscopy can be performed again. At the predetermined time, the intermittent circuit works again and cuts off the exposure circuit, and so on, to achieve the purpose of automatic control of exposure and intermittent exposure.Figure 32-2 …

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