JPH0141200Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power supply synchronized pulsed X-ray generator. In particular, the present invention relates to a circuit that monitors the generation phase and pulse width of pulsed X-rays relative to a commercial power source using a clock synchronized with the commercial power source.

[Conventional technology]

In a power supply synchronized pulsed X-ray generator,
The pulsed X-ray generation phase and pulse width with respect to the phase of the power supply voltage are controlled to be constant in principle. However, if for some reason the X-ray pulse generation phase shifts and the pulse width becomes wider, there is a risk that the subject (patient) being examined will be exposed to excessive X-rays.

Therefore, to check whether there is any abnormality in the timing of supplying high-voltage current to the X-ray tube, a bleeder resistor, which is a voltage dividing resistor, is inserted in parallel to the X-ray tube, and the voltage generated across this bleeder resistor is detected. A technique has been proposed for detecting a failure by detecting a mismatch between the timing at which a high-voltage current appears and the timing at which a high-voltage current is applied to an X-ray tube (Japanese Utility Model Publication No. 56-299920).

[Problem that the invention attempts to solve]

However, in the method of detecting the voltage applied to the X-ray tube, the stray capacitance of the high-voltage cable etc. causes the divided voltage signal appearing at the voltage dividing resistor to be rounded, resulting in a distorted waveform. For this reason, a pulse circuit with an insensitive period is required to prevent a fault from being erroneously detected due to a distorted waveform, resulting in the problem of a complicated circuit configuration.

The present invention solves the above-mentioned drawbacks by providing a pulsed X-ray generator that can simplify the configuration of a monitoring circuit that constantly monitors the generation phase and pulse width of pulsed X-rays and sends out an alarm output. The purpose is to provide.

[Means for solving problems]

The present invention includes an X-ray tube, a current supply circuit that periodically supplies pulsed current to the X-ray tube in synchronization with a commercial power supply, and a high-voltage transformer that supplies high-voltage power to the current supply circuit. In a pulsed X-ray generator, a current detection resistor is inserted in series between the current supply circuit and the X-ray tube, and detection is performed by detecting that a current exceeding a predetermined value has flowed through the current detection resistor. A current detection circuit that generates an output, a clock generation circuit that is connected to the primary winding of the high voltage transformer and generates a clock synchronized with the commercial power supply, and a current supply circuit that generates a current from the clock supplied from this clock generation circuit. a timing circuit that outputs a timing signal that identifies the period during which the current is supplied; and a timing other than the timing at which the output current of the current supply circuit is allowed to be supplied by inputting the output timing signal of this timing circuit and the detection output of the current detection circuit. The present invention is characterized by comprising a logic circuit that generates an alarm output when there is an output of the current detection circuit at a time of .

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a pulsed X-ray generator according to an embodiment of the present invention. In FIG. 1, the primary winding of a high voltage transformer ₁ is connected to a commercial power supply voltage V1. The secondary winding of the high voltage transformer 1 is connected to the input of the current supply circuit 2. X of current supply circuit 2
A ray tube anode voltage and a grid bias voltage are connected to the anode and grid of the x-ray tube 3, respectively.

A feature of the present invention is a pulsed X-ray pulse generation phase monitoring portion surrounded by a dashed line. That is, a low resistance 4 is connected to the cathode of the X-ray tube 3, and the voltage across this resistance 4 is connected to a current detection circuit 5. This current detection circuit 5 detects the detection tube current when the voltage at both ends is above a predetermined value.
Send Ip′. The commercial power supply voltage V ₁ is branched and connected to the clock generation circuit 6.
A clock CK synchronized with the power supply voltage _V1 is connected to the timing circuit 7. The timing circuit 7 generates a timing signal T ₀ in synchronization with the clock CK, such that no tube current Ip can exist in the X-ray tube 3 under normal conditions. Detection tube current from current detection circuit 5
Ip′ and timing signal T ₀ from timing circuit 7
and are respectively connected to the inputs of the AND gate 8. The output of AND gate 8 is connected to set input S of SR type flip-flop 9. S.R.
The reset input R of the type flip-flop 9 is connected to the input terminal of the reset signal, and the error signal Ep is sent out from the output Q.

The operation of the pulsed X-ray generator having such a configuration will be explained. Figure 2 is a time chart of the electrical signal waveform of the pulsed X-ray generator of the present invention, Figure 2a is a time chart when the pulsed X-ray generation phase is normal, and Figure 2b is the pulsed This is a time chart when the line generation phase is not normal. A voltage V ₁ of a commercial power supply is boosted to a high voltage by a high voltage transformer 1 and input to a current supply circuit 2 . The rectified voltage from the current supply circuit 2 is supplied to the anode and cathode of the X-ray tube 3.
A bias voltage is applied to the grid, and the tube current Ip
flows, and the subject is exposed to pulsed X-rays from the X-ray tube 3. The voltage generated across the resistor 4 due to the tube current Ip is input to the current detection circuit 5, and the current detection circuit 5 outputs a shaped detection tube current Ip' having a logical value of "1". Further, the voltage V ₁ of the commercial power supply is input to the clock generation circuit 6, and the clock CK synchronized with the voltage V ₁ is outputted from the clock generation circuit 6. Clock CK is input to timing circuit 7,
The timing signal T ₀ is output from the timing circuit 7 in synchronization with the power supply voltage V ₁ and has a logic value of "1" during a period in which the tube current Ip cannot exist under normal conditions, and has a logic value of "0" during other periods. Detector tube current Ip' and timing signal _T0 are input to AND gate 8, respectively.

Now, when the phase and pulse width of the tube current Ip are normal, as shown in FIG. However, if for some reason the phase of the tube current Ip is shifted and the pulse width is not normal, as shown in FIG. An error signal Ep is sent out. This error signal Ep causes the operator to perform an emergency stop operation.
Alternatively, an automatic stop device can be activated by the error signal Ep. This error signal
Ep can be reset by inputting a reset signal to the reset input R of the SR flip-flop 9.

[Effect of idea]

As explained above, since the detected current signal does not have a distorted waveform, the present invention does not require a circuit configuration to provide a dead period corresponding to the distorted waveform, and generates pulsed X-rays. This has the effect of greatly simplifying the circuit configuration for monitoring the phase and pulse width. Furthermore, since the clock generation circuit is connected to the primary side of the commercial power supply, there is an advantage that no special timer circuit, high voltage switching circuit, etc. are required.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a pulsed X-ray generator according to an embodiment of the present invention. Figure 2 is a time chart of the electrical signal waveform. 1... High voltage transformer, 2... Current supply circuit, 3
...X-ray tube, 4...Resistor, 5...Current detection circuit,
6...Clock generation circuit, 7...Timing circuit, 8...And gate, 9...SR type flip-flop, CK...Clock, Ep...Error signal, Ip...Tube current, Ip'...Detection tube current , T ₀ ...
Timing signal, V ₁ ... power supply voltage.

Claims (1)

[Claims for Utility Model Registration] An X-ray tube 3, a current supply circuit 2 that supplies a pulsed current periodically in synchronization with a commercial power supply to the X-ray tube, and a high-voltage power supply that supplies this current supply circuit with a pulsed current periodically. A pulsed X-ray generator comprising a high-voltage transformer 1, a current detection resistor 4 inserted in series between the current supply circuit and the X-ray tube, and a current of a predetermined value or more flowing through the current detection resistor. Current detection circuit 5 that detects current flow and generates a detection output
and a clock generation circuit 6 connected to the primary winding side of the high-voltage transformer and generating a clock synchronized with the commercial power supply, and identifying the period during which the current supply circuit supplies current from the clock supplied from this clock generation circuit. a timing circuit 7 that outputs a timing signal to output the current, and a timing circuit 7 that receives the output timing signal of this timing circuit and the detection output of the current detection circuit as input, and outputs the current at a time other than the timing when the output current of the current supply circuit is allowed to be supplied. 1. A pulsed X-ray generator comprising logic circuits 8 and 9 that generate an alarm output when there is an output from a detection circuit.