JPH0532959Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention rectifies AC power and supplies it to a capacitor, controls the charging voltage of this capacitor with a chopper to a voltage corresponding to the set tube voltage, and converts this into an inverter. This is an inverter-type X-ray device that converts the voltage into alternating current, boosts it with a high-voltage transformer, rectifies it with a high-voltage rectifier, and supplies it to the X-ray tube to emit X-rays. The inverter-type
This relates to line equipment.

[Conventional technology]

In conventional inverter-type X-ray equipment, the switch that charges the capacitor that provides the X-ray tube operating energy required for X-ray radiation is closed even during X-ray radiation, and when the X-ray radiation is performed, the capacitor is insufficient. It was configured such that energy could be supplied supplementally from the AC power source. In other words, the AC power source is premised on having conditions (capacity, etc.) that allow the capacitor to supply insufficient energy.

[The problem that the idea aims to solve]

For this reason, even if this type of inverter-type X-ray device is installed in a car for mass medical examinations, it may become unusable if the capacity of the AC power source at the medical examination site is small. Therefore, the capacitance of the capacitor is increased to the extent that it satisfies the maximum expected X-ray imaging conditions (tube voltage, tube current, X-ray emission time, etc.), and the switch is opened during X-ray emission.
In other words, it is conceivable to construct the X-ray tube so that all of the operating energy for the X-ray tube during X-ray emission is supplied from the capacitor.

FIG. 2 is a circuit diagram showing such an inverter type X-ray apparatus. In FIG. 1, 1 is an AC power source (usually a commercial AC power source), and when a main circuit electromagnetic contactor (not shown) is turned on and its contact (capacitor charging switch) 2 is closed, this AC power source 1 is turned on. It is supplied to a rectifier 5 via a fuse 3 and an isolation transformer 4. The DC output from rectifier 4 is applied to capacitor 6 to charge it. In this case, the capacitance of the capacitor 6 is selected to be a value sufficient to satisfy the expected maximum X-ray imaging conditions (tube voltage, tube current, X-ray emission time, etc.).

The charging voltage of the capacitor 6 is controlled by a chopper circuit 7 to a voltage corresponding to the set tube voltage, and then converted to alternating current by an inverter circuit 8. The output AC of this inverter circuit 8 is boosted by a high voltage transformer 9 and rectified by a high voltage rectifier 10. The output voltage of this high-voltage rectifier 10 is applied to the X-ray tube 11, and X-rays are emitted.

During this X-ray emission, the contact point (capacitor charging switch) 2 of the electromagnetic contactor is open, so all of the X-ray tube operating energy during X-ray emission is transferred to the capacitor 6.
is supplied by the charging charge of Therefore, such an inverter-type X-ray device can be used even if the capacity of the AC power source 1 is small, and it is considered that it can be easily applied to mass medical examinations mounted on a car.

However, if the capacitor charging switch 2 is open during X-ray radiation, the capacitor charging switch 2 can be used even if the capacity of the AC power supply 1 is small, but the capacitor 6
The following problems occurred when charging. That is, when charging the capacitor 6, the charging current value is large at the beginning of charging and becomes smaller as charging progresses. For this reason, the AC power source 1 used must be able to cover the maximum current at the initial stage of charging, and as a result, there is a problem that it cannot be used when the capacity of the AC power source 1 is small.

An object of the present invention is to provide an inverter-type X-ray apparatus that can be used satisfactorily even with a small-capacity AC power supply and that can be easily applied to mass medical examinations mounted on a car.

[Means to solve the problem]

The above purpose is to rectify the AC power supply and apply it to the capacitor, control the charging voltage of this capacitor to a voltage according to the set tube voltage using the chopper circuit, convert this to AC using the inverter circuit, and boost the voltage using the high voltage converter. In an inverter-type X-ray device that rectifies the rectifier with a high-voltage rectifier and supplies it to the X-ray tube to emit X-rays, a capacitor charging device is provided on the input side of the capacitor, and the circuit is closed when the capacitor is charged and is opened when X-rays are emitted. This is achieved by providing a constant current switch and a constant current circuit that constantizes the charging current of the capacitor.

[Effect]

Since the capacitor charging switch is open during X-ray emission, if the capacitance of the capacitor is increased to the extent that it satisfies the maximum expected X-ray imaging conditions, the X-ray tube operating energy during X-ray emission can be reduced. all of which can be supplied from the capacitor,
During X-ray radiation, even an AC power source with a small capacity can be used.

The constant current circuit makes the charging current constant when charging the capacitor. Generally, a constant current circuit maintains a constant current at a current value lower than the maximum current value before constant current, and this constant current circuit is no exception. Therefore, there is no maximum current at the initial stage of charging, and the capacitor is charged with a current lower than this maximum current, so that an AC power source with a small capacity can be used even when charging the capacitor.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of an inverter type X-ray apparatus according to the present invention. In FIG. 1, the same reference numerals as in FIG. 2 indicate the same or corresponding parts. 12 is a constant current circuit that constantizes the charging current of the capacitor 6, and includes a current detection circuit 12a.
, a variable impedance element, here an NPN type transistor 12b, a comparator 12c, and a reference voltage generator 12d.

In this case, the current detection circuit 12a detects the current flowing through the rectifier circuit 5, that is, the charging current of the capacitor 6, in terms of voltage when charging the capacitor 6. The reference voltage generator 12d outputs a reference current value corresponding to a desired capacitor charging current value (of course, this value is lower than the maximum current when charging the capacitor 6 in the conventional device) in terms of voltage. The comparator 12c is connected to the current detection circuit 12.
The output voltage V ₁ (capacitor charging current detection value) of a and the reference voltage output from the reference voltage generator 12d
Compare V _s (desired capacitor charging current value) and
A signal inversely proportional to the difference (V ₁ -V _s ) is applied to the base of transistor 12b. transistor 12
b is inserted in the forward direction between its collector and emitter into the current carrying path of the rectifier circuit 5, and the impedance between the collector and emitter is controlled by the output signal of the comparator 12c, and the impedance value is is directly proportional to the magnitude of the output signal.

Next, the operation will be explained. Since there is no particular difference in the normal X-ray emission operation from that of the conventional device, the operation of the constant current circuit 12 will be mainly described. Now, prior to X-ray radiation, when the contact point (capacitor charging switch) 2 of the electromagnetic contactor is closed, DC current from the rectifier 5 is supplied to the capacitor 6, and charging is started. When charging of the capacitor 6 is started, the current detection circuit 12a outputs the detected charging current value in terms of voltage. Comparator 12c controls the impedance of transistor 12b so that the output voltage from current detection circuit 12a is equal to the reference voltage from reference voltage generator 12d. As a result, the charging current of the capacitor 6 is controlled to a desired current value (constant value) according to the reference voltage from the initial stage to the final stage of charging, and therefore, even when charging the capacitor, the AC power supply 1 with a small capacity can be used. Become.

As described above, the capacitor charging switch 2 is open during X-ray radiation, so that even during X-ray radiation, the capacity of the AC power source 1 can be small.

[Effect of idea]

According to the present invention, the capacitor charging switch is opened during X-ray emission so that all of the X-ray tube operating energy during X-ray emission is supplied from the capacitor, and the capacitor charging current is made constant. Since the current value is controlled to a desired value (constant value) from the initial stage to the final stage of charging, it can be used satisfactorily even with a small capacity AC power supply, and has the advantage that it can be easily applied to mass medical examinations mounted on a car. .

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the device of the present invention;
FIG. 2 is a circuit diagram of an inverter-type X-ray apparatus in which a capacitor charging switch is opened during X-ray emission so that all of the X-ray tube operating energy during X-ray emission is supplied from the capacitor. 1... AC power supply, 2... Magnetic contactor contact (capacitor charging switch), 3... Fuse, 4
...Isolation transformer, 5 ... Rectifier, 6 ... Capacitor, 7 ... Chopper circuit, 8 ... Inverter circuit, 9 ... High voltage transformer, 10 ... High voltage rectifier, 1
1...X-ray tube, 12...constant current circuit.

Claims (1)

[Scope of utility model registration request] The alternating current is rectified and applied to the capacitor, the charging voltage of this capacitor is controlled by the chopper circuit to a voltage according to the set tube voltage, this is converted to alternating current by the inverter circuit, the voltage is boosted by the high voltage transformer, and then the high voltage rectifier In an inverter-type X-ray device that rectifies the rectifier and supplies it to an X-ray tube to emit X-rays, a capacitor charging switch is provided on the input side of the capacitor, and is closed when the capacitor is charged and opened when X-rays are emitted; An inverter-type X-ray apparatus comprising: a constant current circuit that constantizes the charging current of the capacitor.